tag:blogger.com,1999:blog-73152367077287595212014-07-30T15:56:15.501-06:00Dispatches From Turtle IslandObservations That Transcend Law and PoliticsAndrew Oh-Willekehttp://www.blogger.com/profile/02537151821869153861noreply@blogger.comBlogger673125tag:blogger.com,1999:blog-7315236707728759521.post-6743619116663224552014-07-14T08:30:00.001-06:002014-07-14T08:59:09.867-06:00Bubonic Plague In China<b>Summary</b><br /><br /><a href="http://en.wikipedia.org/wiki/Black_Death#Infection_and_migration">Modern genetic techniques</a> and assimilation of global historical accounts have revealed that the Black Plague that devastated Europe in the Middle Ages, originated in Asia and arrived via the Silk Road trade route. &nbsp;To recap some key dates (all in the current era):<br /><br />* Yuan Empire, China 1331<br />* Hebei Province, China 1334 (the province that surround the Beijing province in northern coastal China)<br />* Persia 1335<br />* Kyrgyzstan 1338-1339<br />* Kaffa, Crimea 1344<br />* Syria 1345-1348<br />* Mecca, Saudi Arabia 1349<br /><br />Kublai Khan's Yuan Empire with a capitol in Beijing, included by 1294 CE, all of modern China except the Tarim Basin, all of Mongolia and Korea, and some of the adjacent territory in what is now Russia to the North of Mongolia and Manchuria. The Yuan Dynasty extended from 1271 CE to 1368 CE, not quite a century, and not long after the plague ravaged China. (The long lived Ming Dynasty originating in Southern China followed the Yuan Dynasty).<br /><br /><b>Analysis</b><br /><br />The role of the expanding plague and the depopulation and chaos left behind in its wake also makes the rapid expansion of the Mongolian Empire resemble much more closely than is commonly realized, the expansion of European conquest in the New World following the arrival of Columbus, and small pox, in 1492 CE. The Golden Horde may have accumulated plague immunity by the time it reached Europe.<br /><br />The backdrop of the plague also helps explain the population genetic impact of the Mongol Dynasty in Asia, since it swept into a population bottleneck that subsequently expanded. And, it explains the fall of the Yuan Dynasty in China itself.<br /><br /><b>Sources</b><br /><br />According to <a href="http://asianhistory.about.com/od/asianenvironmentalhistory/p/Black-Death-In-Asia-Bubonic-Plague.htm">one not particularly reliable source</a>, which I nonetheless have no particular reason to doubt:<br /><blockquote>Many scholars believe that the Black Death began in north-western China, while others cite south-western China or the steppes of Central Asia. We do know that in 1331, an outbreak erupted in the Yuan Empire; it may have hastened the end of Mongol rule over China. In 1334, this disease killed 5 million people in Hebei Province - about 90% of the population. &nbsp;As of 1200, China had a total population of more than 120 million, but a 1393 census found only 65 million Chinese surviving. Some of that missing population was killed by famine and upheaval in the transition from Yuan to Ming rule, but many millions died of bubonic plague.<br /><br />From its origin at the eastern end of the Silk Road, the Black Death rode trade routes west. At Central Asian caravanseries and Middle Eastern trade centers, it infected people all across Asia. . . . <br /><br />Ibn al-Wardi, a Syrian writer who would later die of the plague himself in 1348, recorded that the Black Death came out of "The land of Darkness" (Central Asia). From there, it spread to China, India, the Caspian Sea and "land of the Uzbeks," and thence to Persia and the Mediterranean. &nbsp;The Egyptian scholar Al-Mazriqi noted that "more than three hundred tribes all perished without apparent reason in their summer and winter encampments, in the course of pasturing their flocks and during their seasonal migration." He claimed that all of Asia was depopulated, as far as the Korean Peninsula. (Orent, 106)<br /><br />The Central Asian scourge struck Persia just a few years after it appeared in China - proof, if any is needed, that the Silk Road was a convenient route of transmission for the deadly bacterium. &nbsp;In 1335, the Il-Khan (Mongol) ruler of Persia and the Middle East, Abu Said, died of bubonic plague during a war with his northern cousins, the Golden Horde. This signaled the beginning of the end for Mongol rule in the region. &nbsp;An estimated 30% of Persia's people died of the plague in the mid-14th century. The region's population was slow to recover, in part due to the political disruptions caused by the fall of Mongol rule and the later invasions of Timur (Tamerlane).</blockquote><blockquote class="tr_bq">Archaeological excavations on the shores of Issyk Kul, a lake in what is now Kyrgyzstan, reveal that the Nestorian Christian trading community there was ravaged by bubonic plague in 1338-39. Issyk Kul was a major Silk Road depot, and has sometimes been cited as the origin point for the Black Death. It certainly is prime habitat for marmots, which are known to carry a virulent form of the plague. &nbsp;It seems more likely, however, that traders from further east brought diseased fleas with them to the shores of Issyk Kul. Whatever the case, this tiny settlement's death rate shot up from a 150-year average of about 4 people per year, to more than 100 dead in 1338-39.&nbsp;</blockquote><blockquote class="tr_bq">Although specific numbers and anecdotes are hard to come by, different chronicles note that Central Asian cities like Talas, in modern-day Kyrgyzstan; Sarai, the capital of the Golden Horde in Russia; and Samarkand, now in Uzbekistan, all suffered outbreaks of the Black Death. It is likely that each population center would have lost at least 40% of its citizens, with some areas reaching death tolls as high as 70%.&nbsp;</blockquote><blockquote>In 1344, the Golden Horde decided to recapture the Crimean port city of Kaffa from the Genoese, Italian traders who had taken the town in the late 1200s. The Mongols under Jani Beg instituted a siege, which lasted until 1347, when reinforcements from further east brought the plague to the Mongol lines.<br /><br />An Italian lawyer, Gabriele de Mussis, recorded what happened next: "The whole army was affected by a disease which overran the Tartars [Mongols] and killed thousands upon thousands every day." He goes on to charge that the Mongol leader "ordered corpses to be placed in catapults and lobbed into the city in hopes that the intolerable stench would kill everyone inside."<br /><br />This incident is often cited as the first instance of biological warfare in history. However, other contemporary chroniclers make no mention of the putative Black Death catapults. A French churchman, Gilles li Muisis, notes that a "calamitous disease befell the Tartar army, and the mortality was so great and widespread that scarcely one in twenty of them remained alive." However, he depicts the Mongol survivors as surprised when the Christians in Kaffa also came down with the disease.<br /><br />Regardless of how it played out in fact, the Golden Horde's siege of Kaffa certainly did drive refugees to flee on ships, bound for Genoa. These refugees likely were a primary source of the Black Death that went on to decimate Europe.<br /><br />European observers were fascinated but not too worried when the Black Death struck the western rim of Central Asia and the Middle East. One recorded that "India was depopulated; Tartary, Mesopotamia, Syria, Armenia were covered with dead bodies; the Kurds fled in vain to the mountains." However, they would soon become participants rather than observers in the world's worst pandemic.<br /><br />In "The Travels of Ibn Battuta," the great traveler noted that as of 1345, "the number that died daily in Damascus [Syria] had been two thousand," but the people were able to defeat the plague through prayer. In 1349, the holy city of Mecca was hit by the plague, likely brought in by infected pilgrims on the hajj.<br /><br />The Moroccan historian Ibn Khaldun, whose parents died of the plague, wrote about the outbreak this way:&nbsp;</blockquote><blockquote><blockquote class="tr_bq">Civilization both in the East and the West was visited by a destructive plague which devastated nations and caused populations to vanish. It swallowed up many of the good things of civilization and wiped them out... Civilization decreased with the decrease of mankind. Cities and buildings were laid waste, roads and way signs were obliterated, settlements and mansions became empty, dynasties and tribes grew weak. The entire inhabited world changed.</blockquote></blockquote><b>This source</b> cites, as its sources:<br /><br />* Benedictow, Ole Jorgen. The Black Death, 1346-1353: The Complete History (2004).<br />* Marshall, Robert. Storm from the East: From Ghengis Khan to Khubilai Khan (1993).<br />* McNeill, William Hardy. Plagues and People (1976).<br />* Orent, Wendy. Plague: The Mysterious Past and Terrifying Future of the World's Most Dangerous Disease (2004).<br /><br /><b>Wikipedia</b> cites:<br /><br />* As evidence of the genetic origin of the plague in China, Nicholas Wade (31 October 2010). "Europe’s Plagues Came From China, Study Finds". The New York Times. Retrieved 1 November 2010. This report was actually based upon: G. Morelli et al. (2010) Nature Genetics. December; 42 (12):1140-1143. doi:10.1038/ng.705.<br /><br />* Regarding the Lake Issyk Kul outbreak in Kyrgizstan, Raoult; Drancourt (2008). Paleomicrobiology: Past Human Infections. Springer. p. 152.<br /><br />* The Cambridge History of China: Alien regimes and border states, 907–1368, p.585 for the proposition ("In the 1330s a large number of natural disasters and plagues led to widespread famine, starting in 1331, with a deadly plague arriving soon after."), and<br /><br />* Kohn, George C. (2008). Encyclopedia of plague and pestilence: from ancient times to the present. Infobase Publishing. p. 31. ISBN 0-8160-6935-2, as evidence of an early Chinese outbreak ("The 14th-century plague killed an estimated 25 million Chinese and other Asians during the 15 years before it reached Constantinople in 1347.", i.e. from 1332-1347 CE).<br /><br />* But, Wikipedia notes the lack of a clear medical description of the bubonic plague in China until 1644, relying on Sussman GD (2011). "Was the black death in India and China?". Bulletin of the history of medicine 85 (3): 319–55. doi:10.1353/bhm.2011.0054. PMID 22080795.<br /><br />There is another Wikipedia article <a href="http://en.wikipedia.org/wiki/Black_Death_migration">here</a>&nbsp;that specifically addresses the migration of the Black Plague. &nbsp;It cites regarding the Chinese Outbreak:<br /><br />* McNeill, William H. (1976). Plagues and People. New York: Anchor Books. ISBN 0-385-12122-9.<br /><br /><div class="blogger-post-footer">Copywrite Andrew Oh-Willeke (2012)</div>andrewhttp://www.blogger.com/profile/08172964121659914379noreply@blogger.com0tag:blogger.com,1999:blog-7315236707728759521.post-64008217284893953882014-07-10T18:57:00.002-06:002014-07-10T19:00:22.060-06:00How Big Are The Solid Planets? A Handy Illustration<div class="separator" style="clear: both; text-align: center;"><a href="http://imgs.xkcd.com/comics/surface_area.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://imgs.xkcd.com/comics/surface_area.png" height="317" width="400" /></a></div><br />This excludes Neptune, Saturn and Jupiter, which lack solid surfaces, but includes Moons and minor planets. &nbsp;It is remarkable how much of the solid surface of our solar system is on Earth. &nbsp;Other bodies in the solar system are surprisingly small.<br /><br />This also illustrates some of the limits to accommodating an expanding human population by settling space. &nbsp;Very thinly inhabited parts of the surface of Earth like the Sahara desert, Antarctica, the Australian Outback, Siberia, and the surfaces of the oceans are much more attractive places to live than anyplace that is not on Earth.<div class="blogger-post-footer">Copywrite Andrew Oh-Willeke (2012)</div>andrewhttp://www.blogger.com/profile/08172964121659914379noreply@blogger.com2tag:blogger.com,1999:blog-7315236707728759521.post-91504275934611931282014-07-08T16:22:00.001-06:002014-07-08T16:22:09.835-06:00Discrepancies in CKM Matrix Measurements Not Due To New PhysicsTwo different ways of measuring two of the nine CKM matrix elements (the charm quark to bottom quark and the up quark to bottom quark elements; both of which are tiny relative to the top quark to bottom quark element in this unitary matrix) have produced inconsistent results at a 3sigma plus level.<br /><br />But, a <a href="http://arxiv.org/abs/1407.1320">careful analysis</a> of the kind of new physics that would be necessary to replicate this behavior shows that there is only one theoretically consistent way of achieving the experimentally observed data. &nbsp;The only approach that can fit this data, however, has other implications that much more accurate measurements rule out. &nbsp;Therefore, the analysis appropriately concludes that the apparent discrepancy in the two different ways of measuring these CKM matrix elements is due to underestimated systemic errors (by 50% or more), rather than new physics.<div class="blogger-post-footer">Copywrite Andrew Oh-Willeke (2012)</div>andrewhttp://www.blogger.com/profile/08172964121659914379noreply@blogger.com0tag:blogger.com,1999:blog-7315236707728759521.post-41918384197890785302014-07-07T20:02:00.001-06:002014-07-07T20:02:02.728-06:00Reconciling GR and QCDAn ambitious <a href="http://arxiv.org/pdf/1407.1371v1.pdf">new paper</a> demonstrates in a brief ten pages&nbsp;how to generalize lattice quantum chromodynamics (QCD) (an approach to calculating strong force interactions using the actual equations of the Standard Model in a discrete approximation that is not scale dependent) to incorporate curved space-times, such as&nbsp;the classical version of general relativity.<br /><br />Reconciling the Standard Model to General Relativity is a Holy Grail of fundamental physics.&nbsp; And, even if one can't accomplish this result for both electro-weak interactions and strong force interaction, doing so with the strong force part of the Standard Model is an impressive accomplishment.<br /><br />The ordinary assumption is that GR and the Standard Model can be reconciled only by formulating a new theory of quantum gravity.&nbsp; But, in the case of lattice QCD models, the authors show that QCD and GR can be reconciled using ordinary classical general relativity's equations.<br /><br />As a corollary of this new approach, the authors demonstrate analytically (rather than merely by numerical approximation) for all curved space-times, that QCD does not permit free gluons even in the intense gravitational fields of neutron stars and black holes, contrary to numerous previous speculations that deconfinement (i.e. the existence of particles that are not part of a&nbsp;color charge neutral composite particle) might occur in those circumstances.&nbsp; <br /><br />This paper also paves the way for determining definitively using numerical approximations, if free quarks can exist in strong gravitational fields, and confirms that a quirk of lattice QCD calculations called the double fermion problem is also present in curved space-times.&nbsp; But, the authors reserve resolution of this issue for further resolution.<br /><br /><div class="blogger-post-footer">Copywrite Andrew Oh-Willeke (2012)</div>andrewhttp://www.blogger.com/profile/08172964121659914379noreply@blogger.com0tag:blogger.com,1999:blog-7315236707728759521.post-46353430698008442752014-07-07T12:13:00.000-06:002014-07-07T19:33:07.985-06:00Still No Sign of CPT Symmetry Violations<strong>Overview</strong><br /><br />There is no experimental evidence for CPT symmetry violations&nbsp;to date. CPT symmetry widely believed to be a perfect symmetry, unlike CP symmetry.&nbsp; New experimental data tightens the experimental boundaries on any potential CPT symmetry violations by a factor of up to 100.<br /><br /><strong>Background</strong><br /><br /><em>What is CP Symmetry Violation?</em><br /><br />CP violation is a rare "arrow of time" in the laws of physics.&nbsp; In&nbsp;certain neutral mesons, decays of matter and anti-matter version of the neutral mesons do not decay at the same rates, and the forward and backward versions of these decays occur at different rates.<br /><br />CP symmetry&nbsp;is violated in a few esoteric circumstances driven in the Standard Model entirely by (1) the CP violation phase in the CKM matrix, and (2) the CP violation phase in the PMNS matrix, if any,&nbsp;which governs transitions between neutrino mass states.&nbsp; The latest neutrino physics data favor CP violation in neutrino oscillation, but aren't yet definitive.<br /><br /><a href="http://en.wikipedia.org/wiki/CP_violation#Experimental_status">Experimental evidence of CP violation</a> is restricted to electrically neutral mesons (originally, neutral kaons where it was first observed in 1964; CP violation in other mesons was not observed until 2001), even though, in principle, it is present at tiny levels too small to be detected by current experiments in all weak force interactions of quarks.<br /><br /><em>What is CPT Symmetry Violation?</em><br /><br />CPT violation says that (1) if any physical process proceeds differently starting at one point and ending at another, from the way it would if it started at that end point and ended at that starting point (i.e. reversed in the time coordinate), then (2)&nbsp;the process is identical except that the charge and parity of the interaction is reversed when the direction in time of the process is reversed.<br /><br />CPT symmetry violation also&nbsp;implies a violation of Lorentz invariance. Lorentz invariance means that the laws of special relativity is perfectly observed. Special relativity, in turn, implements to law of nature that says nothing can exceed the speed of light in a particularly elegant way. For example, special relativity modifies Newton's laws of motion because momentum does not translate linearly into acceleration, so that it takes more momentum to produce the same increment of additional velocity as one approaches the speed of light. Special relativity also provides that time slows down in accelerating objects relative to objects at rest with time standing still in the limit of the reference frame of a photon moving at the speed of light.<br /><br /><strong>The New Data</strong><br /><br /><a href="http://arxiv.org/abs/1407.1269">New experimental data</a> from the Large Hadron Collider (LHC) from the decays&nbsp;of electrically neutral B (made of a b quark and an anti-down quark, or&nbsp;their respective&nbsp;anti-particles), B<sub>s</sub> (made of a b quark and an anti-strange quark, or&nbsp;their respective&nbsp;anti-particles) and D mesons (made of a charm quark and an anti-down quark, or their respective anti-particles)&nbsp;tightens already strict experimental constraints on CPT violation.<br /><br />The old constraints on CPT violation are&nbsp;expressed in a formalism where the CPT violation parameter delta alpha sub mu is expressed in units of GeV/c<sup>2</sup> were on the order of 10<sup>-12</sup> to 10<sup>-14</sup>.&nbsp; A smaller parameter means a tighter constraint on any possible CPT violations.<br /><br />Current experimental constraints in neutral kaons (which&nbsp;are made of a strange quark and an anti-up quark, or their respective anti-particles), are much more strict,&nbsp;with limits on the CPT violation parameter delta alpha sub mu of about 2*10<sup>-18</sup> and limits on a related parameter which is of the same order of magnitude in B and B<sub>s</sub> mesons of less than 5*10<sup>-21</sup>.<br /><br />The improvement in the B and B<sub>s</sub> meson cases is two orders of magnitude (i.e. a factor of 100), and in&nbsp; the D meson case by about 1 order of magnitude (i.e. a factor of 10),&nbsp;to&nbsp;new constraints on the order of 10<sup>-14</sup> for D and B<sub>s</sub> mesons and 10<sup>-15</sup> for B mesons without strange quarks. The conclusion to the paper states (with internal cross references omitted):<br /><blockquote>We have presented new results on CPT violation in B<sup>0</sup> and B<sub>s</sub><sup>0</sup> mixing in both the classical and SME [Standard Model Extension] approach, derived from existing BaBar, Belle and LHCb data. In both approaches there is a significant improvement over previous results. LHCb will be able to further improve these numbers in the B<sup>0</sup> and B<sub>s</sub><sup>0</sup> systems, as well as in the D0 system, with dedicated analyses. In most cases these possible LHCb measurements would improve the current best values by orders of magnitude and the corresponding precision on [CPT violation parameter delta alpha sub mu] approaching the interesting region of m<sup>2</sup>/M<sub>Pl</sub>.</blockquote>M<sub>Pl</sub> is the Planck mass, which is about&nbsp;<span class="nowrap">1.2209<span style="margin-left: 0.25em; margin-right: 0.15em;">×</span>10<sup>19</sup>&nbsp;GeV/c<sup>2 </sup></span>the Planck mass is significant in physics because it is related to the point at which the Heisenberg uncertainty principle applies, and quantum rather than classical physics is the only regime that can meaningfully analyze phenomena.<br /><br /><strong>Analysis</strong><br /><br />Very few physics seriously expect there to be CPT violations in meson decays.&nbsp; But, the new experimental evidence confirms this expectation experimentally to unprecedented precision, securing a bedrock principle of fundamental physics.<br /><br />Lorentz invariance violations, where they are theoretically proposed at all, are detectible only over very long distances as a result of quantum gravity theories that propose that space-time is not perfectly continuous and local.<div class="blogger-post-footer">Copywrite Andrew Oh-Willeke (2012)</div>andrewhttp://www.blogger.com/profile/08172964121659914379noreply@blogger.com0tag:blogger.com,1999:blog-7315236707728759521.post-3650397774452613272014-07-02T16:08:00.002-06:002014-07-02T16:11:51.299-06:00CDM Looks Better Relative To WDM With Better ModelsEarlier simulations comparing cold dark matter models (with dark matter particles that are thermal relics with masses on the order of 1-1,000 GeV), with warm dark matter models (with particles typically around 2 keV), reveal that warm dark matter models produce results much more like what we see in the real work than cold dark matter models.<br /><br />But, those simulations contained important simplifications, most critically, not meaningfully including the effects of ordinary baryonic matter on the overall evolution the the large scale structure of the universe and particular galaxies. <br /><br />A <a href="http://arxiv.org/abs/1407.0022">new paper</a> argues that many of the problems that the older models found with CDM models relative to WDM models are fixed in more sophisticated new simulations that appropriately consider the impact of a mix of ordinary baryonic matter and dark matter, rather than simply modeling pure dark matter systems.<br /><br />Meanwhile, an epic 170 paper comprehensively explores alternatives to the standard lambda CDM model of cosmology that modify gravity in the weak gravitational field regime (an idea that started with Milgrom's MOND theory but has many modern variants) rather than relying at all or at least as heavily, on a dark matter hypothesis. &nbsp;Despite its length, it is only a preliminary survey and does not provide a definitive resolution of these questions.<div class="blogger-post-footer">Copywrite Andrew Oh-Willeke (2012)</div>andrewhttp://www.blogger.com/profile/08172964121659914379noreply@blogger.com2tag:blogger.com,1999:blog-7315236707728759521.post-3394208456178662812014-07-02T15:56:00.001-06:002014-07-08T16:25:49.350-06:00Reanalysis of Tevatron Data Disfavors Exotic Particles Under 120 GeV In Higgs DecaysOnce again, the prospects of beyond the Standard Model physics at experimentally accessible scales is looking ever more bleak.<br /><blockquote><b>Tevatron Measurements on Standard Model Higgs</b><br /><br />Federico Sforza, on behalf of the CDF, D0 Collaborations(Submitted on 1 Jul 2014)<br /><br />We present the study of the SM Higgs properties obtained from the combined analysis of the up-to 10 fb−1 dataset collected by the CDF and D0 experiments during the pp¯ collision at s√=1.96~TeV of Tevatron Run II. The observed local significance for the SM Higgs boson signal is of 3.0σ at mH=125 GeV/c2.&nbsp;</blockquote><blockquote>After a brief review of analysis channels contributing the most, where the Higgs boson decays to a pair of W bosons or to a pair of b-quarks jets, the signal production cross section and its couplings to fermions and vector bosons are analyzed. Other presented results are the recent study of the spin and parity of the SM Higgs performed by the D0 collaboration, leading to 3σ level expected exclusion of the JP=0− and JP=2+ hypothesis, and <b>the investigation of exotics final states with invisible decay products of the Higgs, excluded by the CDF collaboration for masses below 120 GeV.</b></blockquote><br />From <a href="http://arxiv.org/abs/1407.0295">here</a>.<br /><br /><b>The Background Context and Minor Conclusions That Reaffirm Prior Data</b><br /><br />Reanalysis of Tevatron experiment data after it shut down and after the LHC discovered the Higgs boson has revealed three sigma evidence of the 125 GeV mass Higgs boson discovered by the LHC.<br /><br />This data also shows that the Higgs boson has W boson and b quark pair decays consistent with a Standard Model Higgs boson's decays. &nbsp;The b quark pair decays are actually the dominant form of Higgs boson decay but are hard to detect in high energy collisions because lots of other non-Higgs boson decays have very similar end states. &nbsp;But, since b quark pair decays account for something like 57% of Higgs boson decays and are the only form of decay into quarks that we expect should be detectable with current experiments, evidence that these decays happen at about the right frequency is critical to confirming the Standard Model nature of the Higgs boson and to ruling out, for example, "lepto-phillic" models of non-Standard Model Higgs bosons.<br /><br />The data rule out pseudo-scalar (at the 3.1 sigma level) and tensor boson (at the 3.2 sigma level) versions of the Higgs boson, leaving the true scalar Higgs boson total angular momentum and parity of the Standard Model Higgs boson as the sole remaining viable option at the 3 sigma level (a few holdout skeptics note that a mix of scalar and pseudo-scalar Higgs bosons is not ruled out quite as strongly, but few really think that this is what we are seeing when all other evidence points so strongly to a Higgs boson indistinguishable from the Standard Model prediction of many decades ago from electro-weak unification theory).<br /><br />All of this is basically old news, however, that has been revealed in previous papers from Tevatron and the LHC previously discussed at this blog. &nbsp;Just click on the Higgs boson tag if you would like to review the prior results on these points.<br /><br /><b>The Big News</b> <br /><br />The critical new development announced in this paper is that it discusses "the investigation of exotics final states with invisible decay products of the Higgs, excluded by the CDF collaboration for masses below 120 GeV." This exclusion is at the 95% confidence level (i.e. two sigma).<br /><br />Ruling out the production of exotic particles with masses of less than 120 GeV in Higgs boson decays is huge! <br /><br />This disproves a huge swath of beyond the Standard Model theories. <br /><br />For example, many beyond the Standard Model theories attempting to provide a dark matter candidate assume the existence of sterile neutrinos that don't couple to the gauge bosons of any of the three Standard Model forces, but do couple to gravity and the Higgs boson. &nbsp;This result largely rules out sterile neutrino candidates of this type with masses of less than 120 GeV.<br /><br />This also extends the exclusion range of an ordinary "fertile" fourth generation neutrino from about 45 GeV to about 120 GeV. &nbsp;There are very sound interpretations of the current experimental evidence to suggest that the heaviest of the three currently known neutrino mass states is lighter than 0.2 eV. &nbsp;Thus, the minimum mass of a fourth generation ordinary neutrino is now about 600,000,000,000 times that of the third generation neutrino (i.e. 6*10^11 times as heavy).<br /><br />More generally, this rules out pretty much all plausible forms of "Higgs portal" dark matter, which has been a leading way to integrate dark matter candidates into the Standard Model framework in a minimalist manner.<br /><br /><b>Impact On SUSY Exclusions</b><br /><br />Increasingly overwhelming experimental evidence, including this latest data point, strongly disfavor the existence of non-Standard Model SUSY particles at the electroweak scale, which was the "natural" mass range at which many original proponents of SUSY theories expected to discover these new particles.<br /><br />Many still popular theories in the parameter space of supersymmetry (SUSY) theories call for "invisible" SUSY particles with masses of under 120 GeV. &nbsp;This new Tevatron data regarding Higgs boson decay products therefore, impacts many theories that might otherwise be considered viable. &nbsp;For example, Lubos Motl&nbsp;<a href="http://motls.blogspot.com/2014/06/stops-at-200-gev-ww-anomaly-may-be.html?m=1">recently discussed</a>&nbsp;a SUSY scenario with at least two invisible sparticles of less than 120 GeV as an attractive model.<br /><br />Also, one of the main reasons to devise SUSY theories in the first place was to address the "hierarchy problem" of the seeming unnaturalness of the many contributions to the Higgs boson mass almost completely cancelling out, through mathematically obvious additional couplings to the Higgs boson that transparently cancel each other out. &nbsp;So, it doesn't work to devise a SUSY theory in which sparticles don't couple to a Higgs boson and can thus escape the impact of the decay product exclusions of the new Tevatron data analysis.<br /><br />The ATLAS experiment at the LHC has <a href="http://arxiv.org/abs/1405.5086">already set</a> higher mass exclusions on SUSY particles, but in more model dependent ways that may not capture as many kinds of Higgs boson decay paths as the Tevatron data:<br /><br /><blockquote>In R-parity-violating simplified models with decays of the lightest supersymmetric particle to electrons and muons, limits of 1350 GeV and 750 GeV are placed on gluino and chargino masses, respectively. In R-parity-conserving simplified models with heavy neutralinos decaying to a massless lightest supersymmetric particle, heavy neutralino masses up to 620 GeV are excluded. Limits are also placed on other supersymmetric scenarios.</blockquote><br />Meanwhile, <a href="http://arxiv.org/abs/1405.4158">CMS experiment at the LHC has ruled out</a> a large range of possible masses for heavy, Standard Model-like Higgs bosons of the type predicted in almost all SUSY theories:<br /><br /><blockquote>A SM-like Higgs boson is excluded in the mass range 248-930 GeV at 95% CL using the shape-based analysis. . . . For the less sensitive cut-and-count analysis we obtain an observed exclusion of 268-756 GeV[.]</blockquote><br />Other constraints, for example from the anomalous magnetic moment of the muon and the total absence of strong SUSY signals in any of the great numbers of channels studies, are discussed <a href="http://dispatchesfromturtleisland.blogspot.com/2014/05/still-no-signs-of-sparticles.html">here</a>, and notes that exclusions are particularly strong for sparticles of less than 300 GeV. Similarly, there is&nbsp;<a href="http://dispatchesfromturtleisland.blogspot.com/2014/01/distinguishing-sm-and-susy-with-running.html">no evidence of SUSY predicted deviations from the Standard Model</a>&nbsp;running of any of the three gauge coupling constants.<br /><br /><a href="http://dispatchesfromturtleisland.blogspot.com/2013/12/natural-susy-exclusions-at-lhc.html">Matt Strassler's recent paper</a> also identified a broad and quite comprehensive exclusion range for SUSY particle masses in "natural SUSY" models. <br /><br />Direct dark matter detection experiments have also<a href="http://dispatchesfromturtleisland.blogspot.com/2013/10/new-direct-detection-limits-on-dark.html"> ruled out WIMP dark matter</a> in the mass range from about 5 GeV to 1000 GeV, the bulk of the low end of the SUSY parameter space for light sparticles.<br /><br />The fact that searches from multiple methodologies all confirm the absence of SUSY particles at these mass scales provides further confidence that this result is a robust one.<br /><br />Exclusions of beyond the Standard Model SUSY particles at single digit TeV scales and higher masses aren't nearly so strong. &nbsp;But, constraints like the expected amount of neutrinoless beta decay in many of those models, and the absence of dark matter models that can fit such heavy lightest supersymmetric particles, as well as their overall minimal impact of experimentally accessible phenomenology from the Standard Model (some of which SUSY theories were motivated to address), all make these versions of SUSY far less interesting and far less well motivated theoretically.<br /><br />UPDATE July 3, 2014:<br /><br />ATLAS has released four pre-prints with new, more demanding SUSY exclusion papers last night. &nbsp;Needless to say, no hint of any SUSY particle was detected in any of the scenarios investigated. &nbsp;Gluinos with masses of less than a bit more than 1 TeV and stop squarks with masses in the low hundreds of GeVs are excluded. <br /><br /><i>SM and SUSY Particles Reviewed</i><br /><br />There are 18 particles in the Standard Model (ignoring color charge variants, antimatter variants of fermions and parity variants of charged fermions):<br />* one scalar spin-0 fundamental particle in the Standard Model (the Higgs boson) that is electrically neutral, lacks color charge and is massive, with antimatter counterparts;<br />* six massive spin-1/2 quarks that are electrically and color charged in three color charged variations each and antimatter variants;<br />* three spin-1/2 charged leptons that lack color charge, with antimatter counterparts;<br />* three spin-1/2 neutrinos that lack electrical or color charge,<br />* one massless electrically neutral spin-1 photons without color charge, with anti-matter counterparts;<br />* one massless electrically neutral, color charged spin-1 gluon that has their eight color charge variants;<br />* two massive electrically charged spin-1 W bosons without color charge which are antiparticles of each other; and<br />* a massive electrically neutral spin-1 Z boson without color charge.<br /><br />Most non-SUGRA quantum gravity theories add one massless spin-2 graviton to the eighteen Standard Model particles. &nbsp;The Standard Model lacks any particle that is a good dark matter candidate. &nbsp;It would be possible to extend the Standard Model with quantum gravity to include a gravitino or right handed sterile neutrinos (and some boson to all their transition to other particle types or between each other), however, without otherwise disrupting the Standard Model.<br /><br />The many particles predicted to exist in a Minimal Supersymmetric Standard Model aka MSSM (and almost all other less minimal SUSY models) are <a href="http://en.wikipedia.org/wiki/Minimal_Supersymmetric_Standard_Model">reviewed at Wikipedia</a>. <br /><br />In addition to a full set of Standard Model particles, the MSSM has five classes of superpartners: squarks (spin 0 bosons that are quark partners), sleptons (spin 0 bosons that are lepton partners), gluinos (spin 1/2 gluon partners), charginos (charged spin 1/2 superpartners of the W bosons and charged supersymmetric Higgs bosons), and neutralinos (four electrically neutral spin 1/2 that are mixes of the superpartners of the W bosons, Z bosons, and Higgs boson). There are also four additional Higgs bosons beyond those in the Standard Model (a positive charged spin zero Higgs ("H+"), a negatively charged spin zero Higgs (H-), a pseudo-scalar Higgs with neutral electric charge (usually denoted "A"), and an extra scalar Higgs with neutral electric charge that is either heavier or lighter than the Standard Model Higgs (usually denoted "H" for the heavier one and "h" for the lighter one). <br /><br />Thus, the MSSM expanded into SUGRA has:<br />* six new scalar bosons that are color and electrically charged (the squarks) in three color charge variation each,<br />* five new scalar bosons are electrically charged but not color charged (the charged leptons, H+ and H-)<br />* five new scalar bosons electrically neutral and not color charged (the sneutrinos, h and A);<br />* one new electrically neutral spin 1/2 fermions (the gluinos) in eight color charge variations;<br />* four new charged spin 1/2 fermions (the charginos) that lack color charge;<br />* four new electrically neutral spin 1/2 fermions (the neutralinos) that lack color charge;<br />* one spin 3/2 fermion (the gravitino) that lacks electrical charge or color charge; and<br />* one massless spin-2 boson (the graviton).<br /><br />The MSSM fermions presumably have anti-matter counterparts.<br /><br />The MSSM conserves R-parity, which has one value of superpartners and the opposite value for non-superpartners, while this is broken dynamically in other SUSY models. &nbsp;There are also SUSY theories that do not perfectly conserve R-parity, although these theories generally provide that the LSP decays to Standard Model particles in R-parity violating decays only very slowly, or with an LSP that is created from Standard Model particles almost as rapidly as it decays into Standard Model particles.<br /><br />In all there are 25 BSM particles in the MSSM (ignoring color charge variants, antimatter variants of fermions, and parity variants of some or all fermions) and an additional 2 in SUGRA (although some people would call the graviton an "honorary" Standard Model particle as it is present in more or less identical forms in almost all supergravity theories) (ignoring antimatter variants of gravitinos, if any).<br /><br />The are experimental hints of the existence of a graviton, but there are no experimental hints of the existence of any of the other 26 BSM particles in the MSSM and SUGRA.<br /><br />The masses of these 26 BSM particles are key parameters, and another key parameter which related to the relationship between the H and h mass, and to the relationship between sfermion and sboson masses in SUSY called tan beta, is another key parameter.<br /><br />None of the MSSM particles are stable except for the lightest supersymmetric particle which cannot decay further because R-parity prevents it from doing so. &nbsp;The LSP then serves as a dark matter candidate. &nbsp;The lightest neutralino and the gravitino are the most attactive as LSP candidates that are also good dark matter candidates because they are massive fermions, lack color charge and electric charge, and are stable.<br /><br />Minimal supergravity (SUGRA) theories have the MSSM particles and also the graviton (massless, spin-2), and a gravitino (the massive, spin-3/2 superpartner of the graviton). &nbsp;Non-minimal SUSY and SUGRA theories often have additional superpartners and non-Standard Model Higgs bosons. &nbsp;Many also have right handed neutrinos and their superpartners, sometimes with a see-saw boson to handle interactions between left and right handed neutrinos that impart mass to neutrinos via a see saw mechanism, and most SUSY and SUGRA theories have Majorana rather than Dirac neutrinos, and conserve B-L number rather than conserving Baryon number and Lepton number separately.<br /><br /><i>BSM particle masses in SUSY and SUGRA theories.</i><br /><br />The only massless BSM particle in the MSSM or SUGRA is the graviton which is also found in Standard Model extensions with quantum gravity.<br /><br />Typically, the mass hierarchy of squarks and sleptons is inverted in SUSY models. &nbsp;Third generation superpartners are the lighest, followed by second generation superpartners, followed by first generation superpartners. &nbsp;Similarly, superpartners of bosons, which are fermions, all have masses greater than their Standard Model (or supersymmetric Higgs boson) counterparts. &nbsp;The possibility that there are any superpartners that are lower in mass than any Standard Model counterparters of the same type has pretty much been completely ruled out experimentally.<br /><br />This does not necessarily mean that the rank order of all Standard Model fermion partner masses is exactly inverted from the mass ranking of the particles in the Standard Model. &nbsp;SUSY theories do not a priori demand, for example that a stau slepton be heavier than a stop squark. &nbsp;But, to simplify matters, many more minimal SUSY models make this assumption. &nbsp;In this case, for example, the lightest sfermion in such a SUSY theory will always be the stop squark, which helps to explain why the search for it is emphasized so heavily relative to other sfermion searches.<br /><br />Also, since most dark matter theories prefer fermions to bosons as dark matter candidates, there should be at least one BSM SUSY fermion which is a partner of a Standard Model (or a partner of a SUSY Higgs boson or graviton) which is lighter than the stop squark (or than the lighest sfermion if different). &nbsp;A SUSY theory in which the stop squark is the LSP is problematic when it comes to providing a good dark matter candidate. &nbsp;Generally speaking, this means that either the lighest neutralino or the gravitino, or both, should be lighter than the stop squark. &nbsp;Since neutralinos are linear combinations of superpartners of Standard Model particles with masses of 80 to 126 GeV, and experimental exclusions for neutralinos appear to be for masses greater than these, this puts an effective floor on the stop squark mass, in a model where the neutralino is the LSP dark matter candidate. &nbsp;If the gravitino is the dark matter candidate (even if the neutralino is actually the LSP), then R-parity conservation for the neutralino is not necessary.<br /><br />One particularly hot issue of scientific debate at the moment is whether there are any flaws in the methodology of SUSY particle searches that would allow any BSM particles in the MSSM or SUGRA with a mass of less than the Higgs boson or top quark to be missed by particle accelerator searches that purport to exclude BSM SUSY or SUGRA particles in the mass ranges. &nbsp;Long lived BSM particles or particles with very low cross-sections of interaction could escape detection, but SUSY and SUGRA theories quite strongly constrain the cross-sections of interaction of the BSM particles that they mandate and provide a framework within which it is possible to qualitatively evaluate particle stability, although SUSY and SUGRA's many parameters do not allow for quantitative evaluations of this stability without additional assumptions about this parameter space not strongly supported by experimental data in any particular case.<br /><br />Thus, a failure to detect a stop, sbottom, stau or tau sneutrino below a certain mass threshold generally also implies that this exclusion also applies lower generation squarks. &nbsp;For example, conclusion that there are no stop squarks below 200 GeV would also imply that there are no scharm or up squarks below 200 GeV.<br /><br />In SUSY theories, all gluinos should have identical masses, the charged Higgs bosons should have masses identical to each other, and the charginos should consist of pairs of particles with opposite charges and identical masses. &nbsp;An exclusion of neutralinos below a certain mass is implied to exclude both the lighest neutralino and all of the other, heavier neutralinos. &nbsp;The differences in couplings between the two scalar Higgs bosons in SUSY theories varies.<br /><br /><i>The New Search Results</i><br /><br />* <a href="http://arxiv.org/abs/1407.0583">Stops squarks</a> ("No significant excess over the Standard Model prediction is observed. A stop with a mass between 210 and 640 GeV decaying directly to a top quark and a massless LSP is excluded at 95% confidence level, and in models where the mass of the lightest chargino is twice that of the LSP, stops are excluded at 95% confidence level up to a mass of 500 GeV for an LSP mass in the range of 100 to 150 GeV. Stringent exclusion limits are also derived for all other considered stop decay scenarios, and generic upper limits are set on the visible cross-section for processes beyond the Standard Model.");<br /><br />*&nbsp;<a href="http://arxiv.org/abs/1407.0608">third generation squarks</a>&nbsp;("A top squark of mass up to about 240 GeV is excluded at 95% confidence level for arbitrary neutralino masses, within the kinematic boundaries. Top squark masses up to 270 GeV are excluded for a neutralino mass of 200 GeV. In a scenario where the top squark and the lightest neutralino are nearly degenerate in mass, top squark masses up to 260 GeV are excluded.");<br /><br />UPDATE July 8, 2014: Another <a href="http://arxiv.org/abs/1407.1043">underwhelming analysis</a> rules out a certain kind of stop squark with masses of under 180 GeV ("[F]or R-parity conserving supersymmetry . . . . Stop masses below ~ 180 GeV can now be ruled out for a light neutralino.") END UPDATE.<br /><br />* <a href="http://arxiv.org/abs/1407.0600">superpartner particles generally</a> ("No excess is observed with respect to the Standard Model predictions . . . Gluino masses up to 1340 GeV are excluded, depending on the model, significantly extending the previous ATLAS limits."); and<br /><br />* <a href="http://arxiv.org/abs/1407.0603">more superpartner particles generally</a> ("No excess above the Standard Model background expectation is observed in the various signal regions and 95% confidence level upper limits on the visible cross section for new phenomena are set. The results of the analysis are interpreted in several SUSY scenarios, significantly extending previous limits obtained in the same final states. In the framework of minimal gauge-mediated SUSY breaking models, <b>values of the <a href="http://en.wikipedia.org/wiki/Supersymmetry_breaking_scale">SUSY breaking scale Lambda</a> below 63 TeV are excluded, independently of tan beta</b>. Exclusion limits are also derived for an mSUGRA/CMSSM model, in both the R-parity-conserving and R-parity-violating case. A further interpretation is presented in a framework of natural gauge mediation, in which the gluino is assumed to be the only light coloured sparticle and gluino masses below 1090 GeV are excluded.").<br /><br />Note that the natural SUSY breaking scale Lambda for a SUSY theory that naturally and fully solve the "<a href="http://en.wikipedia.org/wiki/Hierarchy_problem">hierarchy problem</a>" which was one of the important reasons that SUSY was proposed in the first place is 1 TeV. &nbsp;This is impossible when this Lambda value is at least 63 TeV.<br /><br /><div class="blogger-post-footer">Copywrite Andrew Oh-Willeke (2012)</div>andrewhttp://www.blogger.com/profile/08172964121659914379noreply@blogger.com4tag:blogger.com,1999:blog-7315236707728759521.post-89189622421879069902014-07-02T12:06:00.002-06:002014-07-02T12:15:25.313-06:00Y1K: A Slice of Global History That Shaped The Modern WorldThe time period from around 900 CE to 1100 CE was an eventful one.<br /><br />Austronesian mariners had reached their greatest extent having established their civilization as far as Easter Island (ca. 700 CE-1100 CE), New Zealand (some argue for dates as late as 1250 CE), Hawaii and Madagascar (ca. 350-1000 CE) (in the case of Madagascar together with people who were genetically similar to East African Bantus), and introduced a few South American crops like the kumara to Oceania (reaching the Cook Islands by 1000 CE). &nbsp;Hawaii was first inhabited by Austronesian peoples ca. 300 CE, but around 1000 CE, immigrants from Tahiti called the Pa'ao, introduces a new dynasty of high chiefs, the Kapu system (a comprehensive set of strict religious laws), human sacrifce and the building of heiaus (temples).<br /><br />The Tang dynasty and intermediate Five Dynasties and Ten Kingdoms Period gave way to the Song Dynasty (begun in 960 CE) in China. &nbsp;The Song dynasty ruled all of China until 1127 CE after which it ruled Southern China until 1279 CE. &nbsp;The Song dynasty was marked by a massive central state bureaucracy with posts filled on the basis of civil service exams that rivaled the former Roman Empire and contemporary Islamic empires in scope, but surpassed them in the modernity of its bureaucratic state.<br /><br />The boundaries of modern Islamic South Asia were established, the Gypsies began their wanderings, and the linguistically Dravidian Brahui people migrated to Pakistan from Southern India. <br /><br />Hindu Tagalog peoples created a sphere of cultural influence that reached from Hindu Middle Kingdoms in India to the Phillipines. &nbsp;In Vietnam, the Hindu Kingdom of Champa (ca. 7th century CE to 1471 CE) flourished with significant cultural influence from India. &nbsp;Cambodia's Khmer Kingdom (with its capitol at Angkor Wat) was also a Hindu Kingdom at the time (some later Kings would adopt Buddhism) and would enter its "Golden Age" around 1147 CE. &nbsp;Thailand was ruled by a variety of Dvaravati principalities which were client states of the Khmer Kingdoms loosely allied with each other in a manner not dissimilar to the contemporaneous Holy Roman Empire in Europe. &nbsp;In Western Java, the Hindu Sunda Kingdom (669 CE to 1579 CE) was in its heyday. The Medang Kingdom in Eastern Java vacillated between Hindu and Buddhist influences. &nbsp;In the end, of course, Buddhist replaced Hinduism almost everywhere in Southeast Asia and East Asia. &nbsp;The strong Hindu influences that persisted on the island of Bali in Indonesia are the only successors to this once far flung sphere of Hindu influence (similarly, the Mongolian Empire that rose and fell during Mongolia's late Middle Ages, a few centuries later, has left very little trace of its once vast Asian empire, linguistically or in modern institutions).<br /><br />Around the same time, the city-state of Srivijaya in Sumatra, Indonesia, was a center of Buddhist expansion (another religion with its origins in India) in Southeast Asia and East Asia, which give rise to several Buddhist kingdoms (Kantoli, Srivijaya, Malyu, Pannai and Dharmasraya) that ultimately controlled all of Sumata within the framework of a larger Srivijaya empire. &nbsp;But, this empire was fading around 1000 CE because improved maritime technology allowed ships to skip intermediate ports, and because the Chola state in Southern India attacked Srivijaya's distant city-state holdings. These kingdoms were hubs of maritime trade between India, China and Southeast Asia.<br /><br />In the Mediterranean, the First Crusade, launched by the Pope in 1099 CE, established short lived Christian states in the Levant, Moors were expelled from Northern Iberia from ca. 1000 CE to 1099 CE (reaching Toledo in 1085 CE). Norman soldiers routed the Moors from Southern Italy. Malta acquired its Semitic language at the time. And, conquering Seljuk Turks made Turkey, Turkish speaking and had a roughly 8% population genetic impact on the region. &nbsp;At its peak in 1092 CE, the Seljuk empire included almost all of the Levant, Asia Minor, the Fertile Crescent, the Southern Persian Gulf coast, the Southern Caucasus Mountain region, Iran, Afghanistan, and much of Central Asia.<br /><br />This time period brought about the ethnogenesis of the Druze people of the Levant (ca. 1014 CE to 1043 CE after which they ceased trying to convert newcomers to their faith and turned inward), who may have been refugees from the arrival of the Turks in Iberia. &nbsp;The linguistically Uralic Hungarian language dynasty consolidated their control over Hungary and converted to Christianity (in 1001 CE); their migration to Hungary was likely driven by Turkish expansion. &nbsp;The Roman Catholic and Orthodox Christian churches finally formally split (ca. 1053-1054 CE), more than five hundred years after the fall of Rome.<br /><br />Europe's last hunter-gatherers finally converted to farming and herding. The Holy Roman Empire, formed in 962 CE, was a loose alliance of principalities including most of modern Northern Italy and Germany. The Normans conquered England in 1066 CE. &nbsp;The Viking sailors settled Iceland established one of the first parliaments, the Althing, in 930 CE, and under Lief Erickson, the Vikings established a short lived North American colony of Vinland.<br /><br />Relict animist refugees from the Islamization of Northern Africa and the Sahel led to the ethnogenesis of the astronomy practicing Dogon people in defensible cliff dwellings on the banks of the Niger River in Mali. The Bantu expansion in sub-Saharan Africa reached its greatest extent in Southern Africa and would remain secure there through the present.<br /><br />In the New World, the proto-Inuit Thule people entered North America from Siberia (ca. 500 CE to 1000 CE), possibly sharing a common origin with the expansion of linguistically Uralic people to the West. Some of the Na-Dene people migrated to the American Southwest ca. 1000 CE, giving rise to the Navajo among others, pushed by incoming Inuits and pulled by a power vacuum in the Southwest. &nbsp;Mayan civilization collapsed ca. 950 CE as a result of an extreme drought. The Uto-Aztec language speaking Utes, possible pushed there by the outflows of people from the collapse of the Mayan civilization refugees then replaced the Great Basin's Fremont peoples. The Anasazi people in modern Arizona centered around a religious center a Chaco, developed a culture known for its sophisticated irrigation systems, its precision astronomy, its architecture that led to a baby boom unprecedented in history. The Mississippian culture with a capitol near modern Saint Louis attained regional population densities rivaling modern cities and had a sphere of cultural influence that extended throughout the Mississippi river basin and into the American Southwest as far as the Atlantic Coast of North Carolina.<br /><br />The Cañari people of Ecuador, a small, but advanced civilization, flourished after the fall of the Mayans and before the rise of the Inca and Aztec cultures. And, in modern Acre State, Brazil, deep in the modern Amazonian rain forest, a culture that made massive geoglyphs fully visible only from thousands of feet in the air was in its prime, following in the footsteps of the Nazca Line culture of Peru, and the subsequent Andean Tiwanaku culture which also made geoglyphs.<br /><br />This global ferment was driven in part by climate, the Medieval Warm Period from ca. 950 CE to 1250 CE. Arab astronomers, astronomers attached to the Song Dynasty Court in China, and astronomers in Chaco were witness to a very bright supernova in 1006 CE, to the supernova that created the Crab Nebula on the 4th of July in 1054 CE, and to Halley's Comet in 1066 CE.<br /><br /><div class="blogger-post-footer">Copywrite Andrew Oh-Willeke (2012)</div>andrewhttp://www.blogger.com/profile/08172964121659914379noreply@blogger.com0tag:blogger.com,1999:blog-7315236707728759521.post-17025475197704783972014-06-30T14:03:00.000-06:002014-06-30T14:07:01.184-06:00Cosmic Ray Flux Related To Atmospheric TemperatureCosmic rays, a term that includes not just photons but also fast moving particles headed towards Earth, would kill us all were it not for the protective shield provided by our atmosphere. &nbsp;Analysis of cosmic rays hitting earth are also a key to trying to detect dark matter, the properties of neutrinos, and more.<br /><br />Seasonal variation in these cosmic rays has often been proposed as a key to distinguishing dark matter derived signals from other data. &nbsp;But, it turns out that the strength of the shield that the atmosphere provided against cosmic rays is a function of its temperature.<br /><br />This makes sense. &nbsp;But, a <a href="http://arxiv.org/abs/1406.7019">results from the MINOS experiment</a> quantity this seasonal background factor based on differences in intensity of muon fluxes (which often are produced when cosmic rays strike the atmosphere). &nbsp;This is important because is strongly suggests like seasonal variation in cosmic ray detection that might otherwise be assumed to be a significant signal, is really just due to atmospheric temperature variations.<br /><br />Also, detection of sub-GeV energy dark matter signals requires that neutrinos and other cosmic ray backgrounds be well understood. &nbsp;This kind of stepping stone makes that possible.<br /><br />* * *<br /><br />Precision measurements of neutrinos can also serve as a probe of Lorentz invariance violations (i.e. violations of special relativity), that are expected in some quantum gravity theories. &nbsp;The experimental signatures of Lorentz invariance in neutrino experiments are discussed in <a href="http://arxiv.org/pdf/1406.6838v1.pdf">another new paper</a>.<div class="blogger-post-footer">Copywrite Andrew Oh-Willeke (2012)</div>andrewhttp://www.blogger.com/profile/08172964121659914379noreply@blogger.com0tag:blogger.com,1999:blog-7315236707728759521.post-73000998899024830942014-06-27T21:55:00.000-06:002014-07-03T00:13:19.549-06:00Up Quark, Down Quark Mass Difference Known With Unprecedented Precision<b>The News</b><br /><br />A&nbsp;<a href="http://arxiv.org/pdf/1406.4579.pdf">June 18, 2014</a>&nbsp;paper estimates that differences in electromagnetic field strength between the proton and neutron account for 1.04 +/- 0.11 MeV of the proton-neutron mass difference using lattice QCD methods, an estimate three or four times more precise that previous state of the art estimates of this component. &nbsp;The proton gets more of its mass from its electromagnetic field than the neutron does. &nbsp;(An <a href="http://www.physics.adelaide.edu.au/cssm/workshops/apfb2014/media/presentations/wang_xg.pdf">April 11, 2014 power point description</a> of this paper is also available.)<br /><br />The same paper estimates, using this calculation, that the difference between the up quark mass and the down quark mass is 2.33 +/- 0.11 MeV. &nbsp;This is the most precise estimate of the up quark-down quark mass difference to date. &nbsp;The previous state of the art estimate had a best fit value of 2.5 MeV (within the two sigma confidence interval of the new result), but with an uncertainty of about 0.7 MeV.<br /><br /><b>Some Details For Experts</b><br /><br />The paper assumes that the difference in the strength of the strong force field between the proton and neutron is assumed to be negligible relative to the differences in quark masses and electromagnetic field strengths. &nbsp;This seems intuitively reasonable, because up quarks and down quarks have identical strong force couplings to each other and both have very small masses relative to the total mass of a nucleon, while having very different electromagnetic couplings.<br /><br />Put another way, QCD contributions to the mass splitting between the proton and the neutron are almost entirely a function of the difference between the rest masses of the up and down quarks. &nbsp;This is true even though <a href="http://profmattstrassler.com/articles-and-posts/particle-physics-basics/the-structure-of-matter/protons-and-neutrons/">the gluon field accounts for more than 98% of the mass of protons and neutrons respectively</a>,&nbsp;while the contributions of the rest masses of the quarks themselves is modest.<br /><br />The dominant source of uncertainty in this estimate arises from lack of clarity over whether the dipole form factor of the inelastic subtraction term in the contribution of the electromagnetic field strength to the mass of the proton and neutron scales as a cubic or quartic polynomial (i.e. whether an exponent in an obscure subpart of the overall equation is 3 or 4). &nbsp;If it is cubic, then the actual value is higher by 0.09 and the uncertainty drops from +/- 0.11 MeV to +/- 0.04 MeV. &nbsp;If it is quartic, then the actual value is lower by 0.09 and the uncertainty drops by the same amount. <br /><br />This paper replicated the result of<a href="http://arxiv.org/abs/1406.4088"> another paper</a> released in pre-print form by an independent group of lattice QCD investigators just two days earlier on June 16, 2014, using a moderately different approach, so the result can be considered quite reliable. &nbsp;This paper's result for the difference in mass due to electromagnetic field strength between the proton and neutron is 1.00 MeV +/- 0.16 MeV, and an up quark-down quark mass difference of 2.52 MeV+/- 0.29 MeV. &nbsp;But, it predicts a total difference between the proton and neutron mass of 1.51 +/- 0.28 MeV (compared to the physical value of 1.2933322 MeV), which is not inconsistent with experiment but has a central value that is high by about 16%.<br /><br />Incidentally, while both papers have produced highly precise measurements of the difference in nucleon mass attributable to the electromagnetic field energy in these baryons, I am not able to cite any source regarding the absolute value of this contribution of the masses of the proton and neutron, relative to the contribution from the gluon field in these baryons (and to the extent that the two are interrelated this could conceivably be an ill defined quantity).<br /><br />Both results exploit the <a href="http://journals.aps.org/prd/abstract/10.1103/PhysRevD.26.1194">Coleman-Glashow relation</a>&nbsp;(which dates to at least 1982 or earlier)&nbsp;which argues that the sum of the mass differences in three different pairs of charged and neutral hadrons (one of which is the proton and neutron pair) with carefully chosen combinations of light scalar differences and other factors that cancel out due to symmetries, should equal zero. &nbsp;This hypothesis is confirmed experimentally true to the current limits of experimental precision (something that a <a href="http://www.researchgate.net/publication/222556523_On_the_miracle_of_the_ColemanGlashow_and_other_baryon_mass_formulas">2000 paper</a> called a "miracle", but which flows quite naturally from the quark model of QCD and symmetry considerations).<br /><br /><b>The Masses And Mass Differences Of Exclusively or Predominantly Light Quark Hadrons</b><br /><br /><i>Protons and Neutrons</i><br /><br />A neutron has a rest mass of 939.565,379(21) MeV. &nbsp;A proton has a rest mass of 938.272,046(21) MeV. The difference between the rest mass of the neutron and the rest mass of a proton is known to somewhat greater precision; it is 1.293,332,2(4) MeV.<br /><br />The rest mass of an electron is 0.510,998,928(11) MeV.<br /><br />The difference between the rest mass of a neutron and the sum of the rest masses of a proton and an electron is 0.782,333,2(4) MeV. &nbsp;In other words, this is the minimum energy of a photon produced in ordinary beta decay. &nbsp;About one part in 1201 of the rest mass of a neutron is converted into energy in ordinary beta decay. &nbsp;The other 1200 out of 1201 parts of the rest mass of a neutron is converted in other kinds of rest mass.<br /><br />A neutron has one up quark and two down quarks, producing a zero net electric charge. &nbsp;A proton has two up quarks and one down quark, producing a +1 net electric charge. &nbsp;Both have total angular momentum equal to 1/2.<br /><br />Quantum chromodynamics (QCD) estimates of the proton and neutron mass from first principles are accurate to about +/- 1% (i.e. about +/- 1 MeV), although QCD estimates of the proton-neutron mass difference are now significantly more precise than that (while still remaining far less precise than experimental measurements of this quantity).<br /><br /><i>Other Hadrons Made Up Only Of Up and Down Quarks</i><br /><br />Due to confinement, no light quark is ever observed at an energy scale of less than that of a pion (about 140 MeV for charged pions and 136 MeV for neutral pions), which is the lightest particle made up of quarks, and the only pseudoscalar mesons (total angular momentum of o and negative parity) made up only of light quarks.<br /><br />The vector mesons, with total angular momentum 1, that are made up only of up and down quarks are the rho mesons (vector) (cursive p) which has a mass of 775.11 MeV when charged and 775.49 MeV when neutral, and the omega mesons (vector) (cursive lowercase w) which has a mass of 782.65 MeV.<br /><br />All four of the delta baryons, which are three quark particles made up of combinations of up and/or down quarks with total angular momentum 3/2 (unlike the 1/2 of the proton and neutron) have masses of about 1232 MeV.<br /><br />The lighest scalar meson (with total angular momentum of 0 and positive parity), the f<sub>0</sub>(500) has a mass of about 500 MeV and does not have a consensus interpretation of its makeup in a simple quark composite model, although it is sometimes interpreted as primarily consisting of linear combinations of pions, which are in turn made up only of up and down quarks.<br /><br /><b>Interpreting the Proton-Neutron Mass Difference</b><br /><br />Some of the difference in rest mass between a neutron and proton may be attributable to a difference in mass between an up quark and a down quark. &nbsp;Some of the difference in rest mass between a neutron and a proton may be attributable to a difference in the amount of energy in the strong force field and electromagnetic field in the proton and neutron respectively.<br /><br />To only slightly oversimplify, using the canonical values for the up and down quark masses (discussed further below), the quarks in a proton (about 9.4 MeV) are 2.5 MeV lighter than in the neutron (about 11.9 MeV), but the proton has combined contributions of the strong force fields and electromagnetic fields that are 1.2 MeV stronger (928.9 MeV in the proton v. 927.7 MeV in the neutron), a difference of about a tenth of a percent in field strength.<br /><br />The question of how much of this difference is due to differences between up quark and down quark rest masses, and how much of this differences is due to gluon and photon fields in the proton and neutron is highly model dependent.<br /><br />The particle data group estimate of the mass difference between the up and down quarks is 2.5 MeV, rather than the 1.3 MeV that one would naively expect from the difference between the neutron mass and the proton mass, a value that would struggle to fit in the two sigma error bars of current estimates of absolute masses and mass ratios for these quarks.<br /><br />According to the Particle Data Group, the up quark has an estimated mass of 2.3 MeV + 0.7/-0.5 MeV, and the down quark has an estimated mass of 4.8 MeV +0.5/-0.3 MeV. &nbsp;Viewed together, rather than in isolation, the up quark rest masses is estimated to be from 0.38 to 0.58 of the rest mass of the down quark. &nbsp;The precision with which we know the up and down quark masses is roughly ten million times less than the precision with which we known the difference in rest masses between the proton and neutron. &nbsp;These estimates are little improved from estimates made at the very dawn of the quark model in the 1970s.<br /><br />In late March or early April of 2010, a <a href="http://news.sciencemag.org/physics/2010/04/mass-common-quark-finally-nailed-down">paper in Physical Review Letters by Christine Davies and others</a>&nbsp;(pre-print <a href="http://arxiv.org/abs/0910.3102">here</a>&nbsp;and pdf <a href="http://www.lns.cornell.edu/~qjm3/TwoLoopMass.pdf">here</a>) made a much more precise estimate of 2.01 +/- 0.14 MeV for the up quark and 4.79 +/- 0.16 MeV for the down quark, which implies a difference between the two rest masses of 2.78 +/- 0.21 MeV (and a low end 0.42 mass ratio), which is just barely consistent with the new results at the two sigma level. &nbsp;But, the PDG worldwide average analysis has not proclaimed this result to be correct at that level of precision.<br /><br /><b>Definitional Issues In Light Quark Mass Determinations</b><br /><b><br /></b><i>Light Quark Pole Masses</i><br /><br />Even the definitions of the light quark masses are fraught with problems. &nbsp;In the Standard Model, the mass of a particle varies with the energy-momentum scale at which it is measured. &nbsp;In the case of top quarks, bottom quarks, and charm quarks, it is possible and sensible to measure the "pole mass" of a particle - i.e. the mass of a quark measured at an energy scale equal to its rest mass.<br /><br />In the case of the light quarks, the rest masses of the quarks are customarily evaluated at energy scales of 2 GeV (i.e. at about the mass of two nucleons that collide with each other), at which they are observed (in a confined context), rather than at the rest mass of the quarks themselves. <br /><br />But, for example, extrapolation of the running of the quark masses suggests that the light quarks should be <a href="http://dispatchesfromturtleisland.blogspot.com/2014/02/developments-in-my-own-koides-rule.html">about 35% heavier at a 1 GeV energy scale</a>. &nbsp;Naively extrapolating the running of the light quark masses downward from 2 GeV to estimate their "pole mass" produces masses in the hundreds of MeVs, but a more accurately interpretation is that the pole masses of the light quarks are simply ill defined and the extrapolation is being applied beyond the scale where it is valid. &nbsp;Instead, different definitions of quark masses than pole mass, such as the MS mass scheme are used to generalized the concept of quark masses to the light quarks. &nbsp;But, it isn't obvious that MS mass is as fundamental a quantity as pole mass.<br /><blockquote>Koide (1994) calculates the running of the three light quark masses down to their pole masses, even though these values have little practical application, in both a five quark and three quark flavor model. In the five quark flavor model he comes up with pole masses for the up quark of 346.3 MeV, for the down quark of 352.4 MeV and for the strange quark of 489 MeV. In a three quark flavor model he comes up with pole masses of 163.1 MeV for the up quark, 169 MeV for the down quark, and 338 MeV for the strange quark. One could get somewhat lower light quark pole mass values still in a two quark flavor model.&nbsp;</blockquote><blockquote>Koide updated these calculations in 1997 and concluded that the pole mass of the up quark was 0.501 GeV, the pole mass of the down quark was 0.517 GeV and the pole mass of the strange quark was 0.687 GeV (based on their measured values at other energy scales), although all sub-1 GeV values were noted with an "*" mark.&nbsp;</blockquote><blockquote>A more recent update of the calculations can be found at Xing (2008) does not consider masses running to very low energy scales for light quarks, explaining that "The pole masses of three light quarks are not listed, simply because the perturbative QCD calculation is not reliable in that energy region."</blockquote>Notably, these perturbative QCD calculations become ill defined at masses higher than the mass of the pion. &nbsp;So, perturbative QCD calculations break down to the point of being unreliable at energy scales somewhere between 140 MeV and 1000 MeV.<br /><br />The pole masses in the five quark flavor models are quite similar to the conventional dressed quark masses for the up and down quarks discussed below, however.<br /><br /><i>Dressed Masses For Light Quarks</i><br /><br />Another approach is the look at the <a href="https://www.ntu.edu.sg/ias/upcomingevents/WKSQCD13/Documents/20Mar13_McNeile_Strong%20coupling%20and%20quark%20masses%20from%20lattice%20QCD.pdf">"dressed quark" mass</a> which for the up and down quarks is about 0.32 GeV (i.e. about a third of the proton mass, which is the lightest three quark composite particle containing only light quarks), which includes a proportionate share of the gluon field mass of a baryon that contains a light quark in its mass. &nbsp;This is also sometimes described as a "constituent quark model." &nbsp;(The link in this paragraph is to a 2013 power point presentation that is quite a good starting point for understanding the state of the effort to determine the quark masses.) <br /><br /><a href="http://arxiv.org/abs/1406.7212">Recent state of the art estimates of dressed quark masses</a> determined with Lattice QCD, however, are closer to 0.25 GeV for up and down quarks, and 0.502 GeV for strange quarks. &nbsp;This implies fundamental light quark masses of about 8.6 MeV and fundamental strange quark masses of about 227 MeV at an energy scale of about 840 MeV. &nbsp;These values are about 2.45 times the canonical values for these masses at 2 GeV energy scales. &nbsp;I may be misinterpreting this analysis, but this seems to me to indicate that the total contribution of the electromagnetic field of a proton to a proton's mass is about 188 MeV.<br /><br />While "dressed quark" masses for the up and down quark can produce not obviously wrong estimates of hadron masses for most hadrons containing just up and down quarks (and also, for example, for the eta meson which is a mix of up, down and strange quarks with a mass of 547.85 MeV). <br /><br />But, dressed quark masses for the up and down quarks do seem inconsistent with the masses of the pions. &nbsp;Charged pions have two light quarks but have a mass less than the dressed mass of even one light quark, and neutral pions which are linear combinations of up-antiup and down-antidown quark pairs are even lighter. &nbsp;In constituent quark models, the binding energy of the pion implied by the dressed quark masses for the up and down quarks must be approximately negative 360 MeV. &nbsp;But, it isn't obvious that negative energies are are a physical concept in this context. <br /><br />An alternate way of understanding the light hadron masses which explains why the pion can be so light is explained in a fairly straightforward way <a href="http://www.slac.stanford.edu/econf/C040802/papers/L010.PDF">here</a>. &nbsp;Pions play a special role as "Goldstone" bosons in QCD, i.e. force carriers who arise as a result of a broken symmetry, which give them special properties.<br /><br />Basically, the right formula for the mass of a meson is equal to a constant scale factor times the positive square root of ((two times the average mass of the quarks in the meson) times (the appropriate value for the QCD scale)). &nbsp;The QCD scale value, in turn, is a function of the number of quark flavors that are accessible at the energy level involved. &nbsp;It is about 217 MeV when there is sufficient energy to involve five active quark flavors and abut 350 MeV when there is sufficient energy to involve three active quark flavors. &nbsp;Arguably, it may be necessary in some cases to invoke a two active quark energy scale, although this involves complex self-referential calculations related to the strange quark mass.<br /><br /><b>Footnote</b><br /><br />Another interesting amateur mass hierarchy paper with a numerological flair can be found <a href="http://www.researchgate.net/publication/45856114_Complementary_Quark_and_Lepton_Deviation_from_Mass-Degeneracy_Hierarchies/file/72e7e521cd2f5610bf.pdf">here</a>.<br /><br />UPDATED July 2, 2014 for formatting purposes and to add material to the definitions section of this post.<div class="blogger-post-footer">Copywrite Andrew Oh-Willeke (2012)</div>andrewhttp://www.blogger.com/profile/08172964121659914379noreply@blogger.com0tag:blogger.com,1999:blog-7315236707728759521.post-40691949775992509562014-06-25T13:21:00.001-06:002014-06-25T13:21:17.651-06:00Stray Physics Musings* In the simple Platonic ideal, a black hole is a singularity from which not even light can escape. &nbsp;In other words, photons can't cross the event horizon. &nbsp;In this ideal, whether or not the matter and energy sucked up by a black hole had a net electric charge, the electric and magnetic fields generated by particles with electric charge would not escape the black hole because the photons that give rise to those fields would be trapped behind the event horizon.<br /><br />Now, we know empirically, there is a strong magnetic field in the vicinity of Sagittarius A*, &nbsp;the black hole at the center of the Milky Way. &nbsp;The only way this could be possible in the Platonic ideal of a black hole is if the magnetic field is generated by the movement of charged particles just outside the event horizon as they are pulled toward the black hole. <br /><br />Now, in an ad hoc blend of General Relativity reasoning and quantum mechanics reasoning, have concluded that black holes are leaky, and rather than preventing anything from escaping at all, actually emit Hawking radiation. &nbsp;But, it doesn't necessarily follow that Hawking radiation is large contributor to the magnetic field around black holes that are observed.<br /><br />* In principle, mesons and baryons have an infinite number of excited, higher energy states with higher masses than the ordinary versions of these hadrons. &nbsp;It appears, in contrast, the fundamental fermions come in exactly three generations, rather than an infinite number, which means that an intuitive sense of higher generation fundamental fermions as excitations in the same sense as excited states of hadrons is probably flawed - unless the same process is at work but there is some competing factor that places an upper bound on the amount of excitation that a fundamental fermon can have, but not on a hadron (at least at the energy scales we can observe - one could image that there is exactly some fundamental number of excited states much greater than three that are possible for any given hadron at energies to high to observe).<br /><br />Many factors argue in favor of exactly three generations with current experimental evidence. &nbsp;There are direct lower limits on the possible mass of each of the four possible kinds of fourth generation fundamental fermions. &nbsp;There are also strong theoretical considerations that require each generation to have a complete set of four fundamental fermions.<br /><br />In ratio of limit to mass of third generation fermion, the bound is greatest in the case of the neutrinos. &nbsp;The practical upper bound on the mass of the heaviest Standard Model neutrino rest mass eigenstate is on the order of 0.1 eV/c^2. &nbsp;The lower bound on the mass of a fourth generation neutrino is about 45,000,000,000 eV/c^2. &nbsp;The ratio of the two masses is 450,000,000,000 to 1. &nbsp;This is profoundly greater than any of the ratios of masses between a particle of one generation and a particle of the next generation among the three generations of four kinds of Standard Model fermions. <br /><br />* The Higgs field couples to the rest mass of massive Standard Model particles. &nbsp;But, unlike gravity, it does not couple to mass arising from gluon fields in hadrons, to gluons, to photons, to kinetic energy, to angular momentum, to pressure, or any other quantity besides rest mass that gravity impacts in General Relativity. &nbsp;Yet, since General Relativity describes gravity, and the gravitational effects of rest mass swamp all other sources of gravity in most circumstances, General Relativity must have some fairly deep relationships to the Higgs field. &nbsp;But, the Higgs vacuum expectation value has no seeming correspondence to the cosmological constant aka dark energy.<br /><br />* The most definitive evidence we have for dark matter comes from comparing the behavior of objects observed by astronomers with the behavior we would expect if only General Relativity applied. &nbsp;I strongly suspect that this kind of evidence will be the most powerful means of ultimately discriminating between potential models explaining the mechanism of these effects. <br /><br />For example, we are very near to having a detailed precision map of the shape of the Milky Way dark matter halo that is inferred from a clever method of exploiting the movement of a handful of very special stars which when measured precisely reveal this information in an elaborate variant on triangulation. &nbsp;Increasingly precise measurements of the shape and size of the Milky Way's dark matter halo already permit quite precise estimates of the matter density of dark matter in the vicinity of our sun, which fixes on key parameter in direct dark matter detection experiments. &nbsp;Knowing this from direct halo observations eliminates the model dependence of dark matter detection experiments that merely assume a theoretically estimated dark matter density in our vicinity. &nbsp;Only the mass of individual dark matter particles and their cross section of interaction remain to be determined.<br /><br />Current methods have come up empty in the GeV mass vicinity down to very low cross sections of interaction, and to move to lower mass candidates need to better distinguish and characterize neutrino and cosmic ray backgrounds, although good progress is being made on these fronts. &nbsp;Of course, all is for naught if dark matter is genuinely collisionless, at least with matter other than other dark matter.<br /><br />Accelerator experiments like the LHC also narrow the dark matter particle parameter space. &nbsp;These experiments have likewise come up empty. &nbsp;This strongly disfavors dark matter that interacts via any of the three Standard Model forces, again suggesting that it may be effectively collisionless if it is fermionic (the leading theory) except for Fermi contact forces (since fermions can't occupy the same space at the same time), and any dark matter specific interactions. &nbsp;The lack of Standard Model forces or particles, or General Relativistic equation terms to explain dark matter is really frustrating. &nbsp;We are missing something huge and we don't know why.<br /><br />There are some hints at dark matter annihilation, but these are very model dependent and assume we know about all possible sources of cosmic ray signals when we don't.<br /><br />Computer models that show what the universe would look like given various dark matter properties are also making great strides as greater computational power becomes available.<div class="blogger-post-footer">Copywrite Andrew Oh-Willeke (2012)</div>andrewhttp://www.blogger.com/profile/08172964121659914379noreply@blogger.com0tag:blogger.com,1999:blog-7315236707728759521.post-89203781573460264602014-06-20T18:15:00.001-06:002014-06-20T18:15:29.707-06:00BICEP-2 HedgesAfter peer review, the BICEP-2 paper claiming to observe primordial gravity waves has hedged its conclusions. &nbsp;A presenter at the Moscow Cosmology Conference <a href="http://www.math.columbia.edu/~woit/wordpress/?p=6958">claimed</a> that he has unpublished results due to be released in about six weeks that will show that all or most of the BICEP-2 result is attributable to polarized dust.<div class="blogger-post-footer">Copywrite Andrew Oh-Willeke (2012)</div>andrewhttp://www.blogger.com/profile/08172964121659914379noreply@blogger.com0tag:blogger.com,1999:blog-7315236707728759521.post-25976550558470042522014-06-14T14:47:00.001-06:002014-06-16T15:57:30.459-06:00A Conflict Between General Relativity and Quantum MechanicsOne of the basic issues in fundamental physics is that general relativity and quantum mechanics are theoretically inconsistent. &nbsp;Pointing out exactly why that is the case isn't always easy to understand. &nbsp;One of the key issues is that quantum mechanics relies on a universal standard of time subject only to special relativity, something that does not exist in general relativity. &nbsp;The issue is explored at a physics forum discussion <a href="http://www.physicsforums.com/showthread.php?t=755357&amp;page=2">here</a>.<br /><br />UPDATED June 16, 2014:<br /><br />You can capture some of the flavor in the following discussions:<br /><blockquote>"When one introduces realistic clocks, quantum mechanics ceases to be unitary and a fundamental mechanism of decoherence of quantum states arises. We estimate the rate of universal loss of unitarity using optimal realistic clocks. In particular we observe that the rate is rapid enough to eliminate the black hole information puzzle: all information is lost through the fundamental decoherence before the black hole can evaporate."(http://arxiv.org/abs/hep-th/0406260)<br /><br />"...general relativity is a generally covariant theory where one needs to describe the evolution in a relational way. One ends up describing how certain objects change when other objects, taken as clocks, change. At the quantum level this relational description will compare the outcomes of measurements of quantum objects."(http://arxiv.org/abs/gr-qc/0603090)<br /><br />"...as ordinarily formulated, quantum mechanics involves an idealization. That is, the use of a perfect classical clock to measure times. Such a device clearly does not exist in nature, since all measuring devices are subject to some level of quantum fluctuations. The equations of quantum mechanics, when cast in terms of the variable that is really measured by a clock in the laboratory, differ from the traditional Schroedinger description. Although this is an idea that arises naturally in ordinary quantum mechanics, it is of paramount importance when one is discussing quantum gravity. This is due to the fact that general relativity is a generally covariant theory where one needs to describe the evolution in a relational way..."(http://arxiv.org/abs/quant-ph/0608243)</blockquote>But, while "unitarity" has a usual meaning in quantum mechanics to the effect of, all the calculated probabilities of different possibilities add up to 100%, it isn't totally clear that this is real what the authors mean when they talk about unitarity in this context. As Physics Forum moderator Marcus explains:<br /><blockquote>So then the question comes back: what does "unitary" mean, in this field theory context, where we no longer have a "wave function" telling simply the amplitude of a particle to be at some particular place at some moment. I think now unitary means more something like preserving information, or preserving coherence, predictability. It is not as clear what the intuitive meaning is.</blockquote>It is also not clear how much of the "fundamental decoherence" that arises when you try to migrate ordinary quantum mechanics from 4 dimensional Minkowski space where only special relativity holds to the space of general relativity is actually a physical effect, and how much of this is really a function of not being clever enough in how quantum mechanical equations are generalized into a general relativistic context.<br /><br />Obviously, to the extent that a loss of unitarity takes its conventional meaning of the probability of all possibilities adding up to 100%, we know that in the real world, (whose "equations" are properly formulated) the probabilities of all possibilities still do add up to 100%. We don't get "blue screens of death" where the numbers simply don't add up and "nothing" happens, or more than one outcome happens simultaneously, in the same universe, in the real world.<br /><br />But, it could be that the lack of the fixed time scale in general relativity and the probabilistic nature of quantum mechanics, do conspire in the real world to erase "information" that would otherwise be preserved in either of those theories acting alone, although I suspect this might an ambiguity between two or more possible sets of information, rather than infinitely many possibilities, in the real world absent highly contrived circumstances that would never actually occur. <div class="blogger-post-footer">Copywrite Andrew Oh-Willeke (2012)</div>andrewhttp://www.blogger.com/profile/08172964121659914379noreply@blogger.com0tag:blogger.com,1999:blog-7315236707728759521.post-3392159594572022832014-06-12T10:27:00.000-06:002014-06-12T10:27:09.540-06:00Quick Physics Notes* The seven standard deviation difference between ordinary the proton charge radius, and the muonic hydrogen charge radius is greatly exaggerated because <a href="http://arxiv.org/abs/1406.2962">the margin of error of the proton charge radius measurement was greatly underestimated</a>. &nbsp;An accurate MOE for the proton charge radius reduces the discrepancy to four standard deviations.<br /><br />* <a href="http://arxiv.org/abs/1406.2698">Another study</a> finds that dark photons cannot explain the muon anomalous magnetic moment (whose measured value shows a 3.6 sigma discrepancy from the Standard Model prediction). &nbsp;The same data set from 1980-1982 whose implications were not appreciated at the time, also significantly constrains the parameter space of sub-GeV dark matter generally.<br /><br />* A <a href="http://arxiv.org/pdf/1406.2927.pdf">review of the parameter space</a> of a large class of singlet fermion dark matter models (with CDM particle masses up to 1 TeV) which are mediated by an extra Higgs boson are ruled out experimentally.<div class="blogger-post-footer">Copywrite Andrew Oh-Willeke (2012)</div>andrewhttp://www.blogger.com/profile/08172964121659914379noreply@blogger.com0tag:blogger.com,1999:blog-7315236707728759521.post-22639949451764565802014-06-11T14:14:00.001-06:002014-06-11T14:14:30.997-06:00Skull Shapes Differed In The Pre-LGM and Post-LGM Paleolithic EraModern humans arrived in Europe around 40,000 years ago (in very round numbers), replacing Neanderthals by 30,000 years ago. &nbsp;Then, they were expelled from all but a few refugia in Southern Europe, by a catastrophic ice age which peaked at the Last Glacial Maximum (LGM) ca. 20,000 years ago, when most of Northern Europe was covered by glaciers because the average global temperature was about 4.5 degrees colder than it is today. &nbsp;As the glaciers receded, over a period of several thousand years after the LGM, modern humans repopulated Europe from the refugia and from outside of Europe entirely.<br /><br />An analysis of skull shapes shows that pre-LGM Cro-Magnon modern humans had significantly different skull shapes than post-LGM Paleolithic modern humans, than early Neolithic era modern humans, and than modern humans in approximately their modern form a few thousand years after that.<br /><br />A <a href="http://dienekes.blogspot.com/2014/06/craniometric-discontinuity-at-last.html">new study</a> of these skull shapes concludes that about two-thirds of the differences between pre-LGM and modern modern human skull shapes comes from the gap between pre-LGM modern humans and immediately post-LGM Paleolithic modern humans. &nbsp;The next biggest gap was between post-LGM Paleolithic modern humans and early Neolithic modern humans. &nbsp;The smallest gap was between early and late Neolithic and later era modern humans. <br /><br />The study offers no opinion concerning whether this reflects a different genetic makeup or other environmental or epigenetic factors.<br /><br />The study is notable, because it is the first physical anthropology evidence of which I am aware that demonstrates substantial physical anthropology differences between modern humans in Europe before and after the LGM that must have had some cause, even if the exact cause is not known. <br /><br />The data from mtDNA samples, in contrast, have tended to show more continuity between pre-LGM and post-LGM hunter-gatherer populations, which is a bit surprising itself given that we known for sure that there was a total replacement of the human population of most of Europe as a result of the LGM. &nbsp;Autosomal genetic data on pre-LGM modern humans in Europe is so scarce and so preliminary that it is too early to know if it differed materially from post-LGM Paleolithic populations unless you are actually in the labs doing the cutting edge work and have access to inside information as a result.<br /><br />While analysis of skull shape is largely out of favor in anthropological and social scientific circles, for the very good reason that this data was grossly misapplied and misused in the 19th century hey day of this kind of scientific investigation in physical anthropology, that doesn't mean that modern studies taking this approach in the far more restrained context of modern scientific knowledge, are worthless. &nbsp;They tell us something, just not as much as 19th century proto-scientists thought that they did.<div class="blogger-post-footer">Copywrite Andrew Oh-Willeke (2012)</div>andrewhttp://www.blogger.com/profile/08172964121659914379noreply@blogger.com3tag:blogger.com,1999:blog-7315236707728759521.post-63039039892682247922014-06-11T13:57:00.002-06:002014-06-11T13:57:53.440-06:00Neanderthal Admixture and Racial Phenotypes In Modern HumansAnalysis of the recovered ancient Neanderthal genome strongly suggests that they had very light pigmentation in hair, skin and eyes. &nbsp;Put simply, Neanderthals were white. &nbsp;Ancient DNA also suggests that the earliest modern humans in Europe, called Cro-Magnons, were dark pigmented relative to modern Europeans. &nbsp;Simply put, Cro-Magnons were "brown" (but did not have the modern sub-Saharan African phenotype, associated with the folk racial classification "black" in the United States, either).<br /><br />The questions is whether light pigmentation in some modern humans in Eurasia arose from admixture with Neanderthals. &nbsp;The Neanderthal light pigmentation genes aren't identical to the modern European light pigmentation genes, but a <a href="http://dienekes.blogspot.com/2014/06/neandertal-origin-of-mc1r-haplotypes.html">new paper</a> makes a tentative case that most of the light pigmentation genes in aboriginal Tawainese people, and to a much lesser extent in some other Eurasians (especially East Asians), could have a Neanderthal source. <br /><br />I'm agnostic regarding how solid this evidence is at this time. &nbsp;Maybe the paper makes a really strong case for this, but I'm not convinced by what I have read summarizing the paper so far.<div class="blogger-post-footer">Copywrite Andrew Oh-Willeke (2012)</div>andrewhttp://www.blogger.com/profile/08172964121659914379noreply@blogger.com3tag:blogger.com,1999:blog-7315236707728759521.post-9484841145104387062014-06-10T15:15:00.002-06:002014-06-14T12:59:49.918-06:00Thoughts On The Matter-Antimatter Imbalance In The Universe<b>Background</b><br /><br />Every Standard Model process except an extremely high energy and exotic theoretically possible process called a sphaleron, separately conserves baryon number (i.e. quarks minus anti-quarks divided by three), and lepton number (i.e. leptons minus anti-leptons). &nbsp;Even sphalerons conserve B-L.<br /><br />But, the baryon number of the universe (essentially equal to the combined number of protons and neutrons in the universe) is a high positive number since anti-matter baryons are extremely rare. &nbsp;The same is true of charged leptons which are almost exactly equal in number to the number of protons in the universe; positrons, anti-muons and anti-tau leptons are all extremely rare.<br /><br />There are far more neutrinos in the universe than there are baryons and charged leptons combined. &nbsp;But, it isn't obvious what the ratio of neutrinos to anti-neutrinos is in the universe, although there are hints that the number of anti-neutrinos greatly exceed the number of neutrinos.<br /><br />Even the number of anti-neutrinos measurably exceeds the number of neutrinos in the universe, the excess of anti-neutrinos over neutrinos creates a negative lepton number for the universe that swamps the total positive baryon number of the universe and the positive lepton number from charged baryons in the universe. &nbsp;Thus, B is a very large positive number, L is probably an even larger negative number, and B-L is a very large positive number.<br /><br />Fundamental dark matter particles that were antimatter and had baryon number, or were matter and had lepton number, could help even the scales a bit. &nbsp;But, given the known total amount of dark matter in the universe and reasonable assumptions about the mass of dark matter particles, no fundamental dark matter particle with either of those properties could resolve the matter-antimatter asymmetry in the universe.<br /><br />Careful analysis has determined that Standard Model sphaleron processes could not account for the current matter-antimatter asymmetries even over the entire history of the universe from a B=0, L-0, and B-L=0 initial condition which is often unquestioningly assumed at the initial moment of the Big Bang.<br /><br /><b>Analysis</b><br /><b><br /></b>So, why does our universe have such a matter-antimatter imbalance for different classes of fundamental particles (i.e. B&gt;&gt;0, probably L&lt;&lt;0, and probably B-L&gt;&gt;0)? <br /><br />There are basically four possible solutions:<br /><br />(1) <i>The Universe Did Not Begin As Pure Energy. &nbsp;</i>The starting point of the universe is not B=0, L=0 and B-L=0. &nbsp;Instead, the universe started with B&gt;&gt;0, L&lt;&lt;0 and B-L&gt;&gt;0 and has preserved those numbers ever since. &nbsp;They are arbitrary laws of the universe just like other physical constants in the Standard Model and General Relativity like the speed of light, or Planck's constant.<br /><br />(2) <i>We Can't Observe Important Balancing Parts Of The Universe. &nbsp;</i>The universe includes places we cannot see due to General Relativistic singularities and balancing baryons and leptons to create B=0, L=0, B-L=0 are on the other side of singularities between us in the observable universe and the relevant event horizons. &nbsp;This has two subcomponents:<br /><br />(a) <i>Before The Big Bang. &nbsp;</i>There was one anti-baryon created for every baryon, but the anti-baryons are overwhelmingly located before the Big Bang and are moving backward in time. &nbsp;Likewise, leptons and/or anti-leptons necessary to balance lepton number are overwhelmingly located before the Big Bang. &nbsp;Antimatter moving forward in time towards the Big Bang, and matter moving backward in time towards the Big Bang fuel this massive energetic event which created particle-antiparticle pairs in large numbers which unequally sorted antimatter particles "before" and matter particles "after". &nbsp;This is very similar in principle to possibility (1).<br /><br />(b) <i>Inside Black Holes. &nbsp;</i>Anti-baryons, positrons, anti-muons, anti-tau leptons, and ordinary neutrinos are disproportionately sucked into black holes relative to baryons, charged leptons, and anti-neutrinos. &nbsp;This sorting could arise from general relativity acting on pair production at the event horizon, or could arise from some other process. &nbsp;For example, if black holes tend to have negative electric charge, they will tend to suck up anti-protons in preference to protons. &nbsp;One fruitful way to investigate this possibility would be to look at the relative matter-antimatter composition of Hawking radiation.<br /><br />[UPDATE June 16, 2014:] Given that <a href="http://dispatchesfromturtleisland.blogspot.com/2013/08/central-black-hole-of-milky-way-has.html">the black hole at the center of the Milky Way galaxy has a strong magnetic field</a>, and appears to be quite typical of black holes at the center of ordinary galaxies, the possibility that black holes are usually charged in a way that biases what does and does not enter a black hole based upon its electric charge which is correlated strongly with matter-antimatter character, is worth taking seriously. [End UPDATE.]<br /><br />(3) <i>The Dark Sector Balances The Books. &nbsp;</i>There are particles in the dark sector (i.e. those that account for dark matter and dark energy phenomena) that have baryon number and lepton number that balance out the matter-antimatter imbalance in observed matter. &nbsp;Note that for the dark sector to contain the correct number of anti-baryons and leptons, and for the total mass of dark matter particles to coincide with the measured value, it is probably necessary for dark matter to be made out of composite particles rather than fundamental particles if the mass of each dark matter particle is in line with estimates inferred from astronomy observations. <br /><br />The inferences one draws in general about the dark sector, if it is to resolve these imbalances (or at least to bring B-L to zero) provide an interesting exercise that depending on the neutrino-antineutrino ratio may imply composite dark matter, dark matter dominated by heavy dark matter particles with a wealth of very light (perhaps neutrino or axion mass scale) particles that have only a minimal effect on cosmic structure because they are so light relative to other kinds of matter in the univese, or even a dark sector in which dark matter phenomena are primarily a function of modified gravity laws rather than dark matter particles (if the neutrino-antineutrino ratio is only every so slightly balanced in favor of antineutrinos, leading to L=0 or L=-B).<br /><br />(4) <i>Beyond The Standard Model Processes Do Not Conserve B and L and B-L. &nbsp;</i>There are additional new physics processes beyond the Standard Model that violate baryon number conservation and lepton number conservation in ways that are almost impossible to observe now, but would have led to baryogenesis and leptogenesis in the highly energetic very early universe immediately after the Big Bang. <br /><br />This is the predominant view among theoretical physicists, but this really shortchanges equally plausible options (1), (2)(a), (2)(b), and (3) without a good reason for doing so.<br /><br />I would note that Option 2(a) is a particularly elegant solution that is also parsimonious, and could be supplemented in part by 2(b) and (3) to some extent that would not have to be complete.<br /><br />It would also be an interesting exercise to determine the total mass-energy of the universe and compare it to the total number of particles in the universe and the total B+L of the universe.<br /><br /><br /><br /><div class="blogger-post-footer">Copywrite Andrew Oh-Willeke (2012)</div>andrewhttp://www.blogger.com/profile/08172964121659914379noreply@blogger.com2tag:blogger.com,1999:blog-7315236707728759521.post-55126563762872292512014-06-09T13:00:00.000-06:002014-06-10T15:35:38.231-06:00Interesting LHCP 2013 (Barcelona) Higgs Conference Abstracts* Francesco Riva, "The Higgs: supersymmetric partner of the neutrino"<br /><blockquote>Recent LHC searches have provided strong evidence for the Higgs, a boson whose gauge quantum numbers coincide with those of a SM fermion, the neutrino. This raises the question of whether Higgs and neutrino may be related by supersymmetry. I will show explicitly the implications of models where the Higgs is the sneutrino: from a theoretical point of view an R-symmetry, acting as lepton number is necessary; on the experimental side, squarks exhibit novel decays into quarks and leptons, allowing to diﬀerentiate these scenarios from the ordinary MSSM.</blockquote>The idea that the Higgs boson itself could be a superpartner of the neutrino is novel and interesting. &nbsp;A <a href="http://arxiv.org/abs/1211.4526">related pre-print</a> discusses the issue. &nbsp;This model is quite interesting, effectively proposing a SUSY model that is even more minimal than the MSSM:<br /><br /><blockquote>We have shown that the phenomenology of this model is quite diﬀerent from that of the MSSM. In the Higgs sector, a sizable (∼ 10%) invisible branching ratio for Higgs decays into neutrinos and gravitinos is possible, together with small deviations in the Higgs couplings to gluons and photons, due to loop eﬀects if the stop t˜R is light. These eﬀects are not yet favored nor disfavored by the present LHC Higgs data, but could be seen in the near future by measuring a reduction of the visible Higgs BRs. Higgsinos are absent in this model, and gauginos must get Dirac masses above the TeV. Only third-generation squarks are required, by naturalness, to be below the TeV. We have shown that the R-symmetry implies that squarks decay mainly into quarks and either leptons or gravitinos. Therefore, evidence for models with the Higgs as a neutrino superpartner can be sought through the ongoing searches for events with third-generation quarks and missing energy (tailored for the MSSM with a<br />massless neutralino) or through leptoquark searches for ﬁnal states with heavy quarks and leptons. In the stop decays into tops and neutrinos, the determination of the top helicity will be crucial to unravel these scenarios.</blockquote><br />Existing LHC searches rule out stops of less than 530 GeV and sbottoms of less than 500 GeV in this model.<br /><br />* Juan Rojo Chacon, "Parton Distributions in the Higgs Boson Era"<br /><blockquote>With the recent discovery of the Higgs boson at the LHC, particle physics has entered a new era, where it is of utmost importance to provide accurate theoretical predictions for all relevant high energy processes for signal, bacground and New Physics production. Crucial ingredients of these predictions are the Parton Distribution Functions, which encode the non-perturbative dynamics determining how the proton’s energy is split among its constituents, quarks and gluons.<br /><br />To bypass the drawbacks of traditional analyses, a novel approach to PDF determination has recently been proposed, based on artiﬁcial neural networks, machine learning techniques and genetic algorithms. In this talk we motivate their relevant of PDFs for LHC phenomenology and describe the latest developements of PDFs with LHC data.</blockquote>The clear description of what the PDF is and why it is important provides useful background context.<br /><br />* Daniele Barducci, Alexander Belyaev, Stefano Moretti and Stefania De Curtis, "The 4D Composite Higgs model and the 125 GeV Higgs like signal at the LHC"<br /><blockquote>General Composite Higgs models provide an elegant solution to the hierarchy problem present in the Standard Model (SM) and give an alternative pattern leading to the mechanism of electroweak symmetry breaking (EWSB). We present a recently proposed realistic realization of this general idea analyzing in detail the Higgs production and decay modes. Comparing them with the latest Large Hadron Collider (LHC) data we show that the 4D Composite Higgs Model (4DCHM) could provide a better explanation than the SM to the LHC results pointing to the discovery of a Higgs like particle at 125 GeV.</blockquote>It is hard to tell from the abstract what the gist of the 4D Composite Higgs Model is, but it is worth looking at<a href="http://arxiv.org/pdf/1310.1201v2.pdf"> preprints</a> to find out. Alas, the larger picture looks abysmally complex and hence less plausible: "Besides the SM particles the 4DCHM present in its spectrum 8 extra gauge bosons, 5 neutral called Z' and 3 charged called W', and 20 new quarks: 8 with charge +2/3, 8 with charge −1/3 and 2 respectively with charge 5/3 and −4/3; these coloured fermions are called t', b', T˜ and B˜, respectively." <br /><br />* Jernej Kamenik, "On lepton ﬂavor universality in B decays"<br /><blockquote>Present measurements of b-&gt;c tau nu and b-&gt;u tau nu transitions diﬀer from the standard model predictions of lepton ﬂavor universality by almost 4 sigma. We examine new physics interpretations of this anomaly. An eﬀective ﬁeld theory analysis shows that minimal ﬂavor violating models are not preferred as an explanation, but are also not yet excluded. Allowing for general ﬂavor violation, right-right vector and right-left scalar quark currents are identiﬁed as viable candidates. We discuss explicit examples of two Higgs doublet models, leptoquarks as well as quark and lepton compositeness. Finally, implications for LHC searches and future measurements at the (super)B- factories are presented.</blockquote>Some of the strongest evidence for beyond the Standard Model behavior involves Lepton flavor violations where decays to electrons are about 25% more common than decays to muons, contrary to a Standard Model expectation of equal frequencies. This is a promising place to look for new physics. Motl discusses the results in a post <a href="http://motls.blogspot.com/2014/06/new-physics-lhcb-insists-on-flavor.html">here</a>.<br /><br />* Jorge de Blas Mateo, "Electroweak constraints on new physics"<br /><blockquote>We brieﬂy review the global Standard Model ﬁt to electroweak precision data. After that we analyze the electroweak constraints on new interactions, following a model-independent approach based on a general dimension-six eﬀective Lagrangian. Finally, we also discuss the limits on several common new physics additions.</blockquote>The abstract again says little, but this methodology is a window into higher energies than direct searches can reveal so it is always interesting to follow up upon at some point in the <a href="http://arxiv.org/pdf/1307.6173v1.pdf">pre-print</a>. Alas, however, the paper has so little analysis and so many undefined quantities (since it basically updates prior papers on the same topic with new numbers) that it is virtually impossible to make any sense of them.<br /><br />* Carlos Lourenco, "Quarkonium production and polarization"<br /><blockquote>All the three frame-dependent polarization parameters (lambda_theta, lambda_phi and lambda_thetaphi), plus the frame-invariant parameter lambda_tilde, are measured in three diﬀerent polarization frames, in ﬁve transverse momentum bins and two rapidity ranges, signiﬁcantly extending the pT and rapidity ranges probed by previous experiments. The observations are in disagreement with the available theoretical expectations.</blockquote>The excerpt of the abstract above captures the key point. Once again, the observed properties of quarkonium have failed to conform to theoretical expectations.<br /><br />From <a href="https://indico.cern.ch/event/210555/abstract-book.pdf">here</a>.<br /><br />* The Conference also, according to Matt Strassler, <a href="http://profmattstrassler.com/2014/06/02/some-higgs-news-from-the-lhcp-conference/">showed convergence in the ATLAS mass measurements of the Higgs boson</a>, but the exact new Higgs boson mass numbers from ATLAS aren't available in the abstracts or his commentary at his blog:<br /><br /><blockquote>[Y]ou may recall a tempest in a teapot that erupted in late 2012, when ATLAS’s two measurements of the Higgs particle’s mass disagreed with each other by more than one would normally expect. This generated some discussion over coffee breaks, and some silly articles in on-line science magazines, even in Scientific American. But many reasonable scientists presumed that this was likely a combination of a statistical fluke and a small measurement problem of some kind at ATLAS. The new results support this interpretation. ATLAS, through some hard work that will be described in papers that will appear within the next couple of days, has greatly improved their measurements, with the effect that now the discrepancy between the two measurements, now dominated by statistical uncertainties, has gone down from nearly 3 standard deviations to 2 standard deviations, which certainly isn’t anything to get excited about. Experts will be very impressed at the reduction in the ATLAS systematic uncertainties, arrived at through significantly improved energy calibrations for electrons, photons and muons.<br /><br />Experts: More specifically, the measured mass of the Higgs in its decay to two photons decreased by 0.8 GeV/c², and the systematic uncertainty on the measurement dropped from 0.7 GeV/c2 to 0.28 GeV/c2. And by the way, the rate for this process is now only 1 standard deviation higher than predicted for the simplest possible type of Higgs (a “Standard Model Higgs“); it was once 2 standard deviations high, which got a lot of attention, but was apparently just a fluke.<br /><br />Meanwhile, for the decays to two lepton/anti-lepton pairs, the systematic error has dropped by a factor of ten — truly remarkable — from 0.5 GeV/c2 to 0.05 GeV/c2. The Higgs mass measurement itself has increased by 0.2 GeV/c2.</blockquote><br />UPDATE: Analysis of these facts in a comment. My previous analysis overlooked statistical error. &nbsp;The report is <a href="https://indico.cern.ch/event/279518/session/9/contribution/10/material/slides/0.pdf">here</a>&nbsp;at page 15.<br /><br />* Beyond the scope of the Conference, I also note that two recent preprints have suggested that the combined ATLAS and CMS data reveal a potential signal of a 200 GeV mass stop sparticle and that there could be several other light sparticles that were overlooked in earlier searches, a possibility which <a href="http://motls.blogspot.com/2014/06/stops-at-200-gev-ww-anomaly-may-be.html?m=1">Motl disucsses in an upbeat way at his blog</a>. <br /><br />Given the number of searches made by ATLAS and CMS combined and the fact that joint data from the two studies is necessary to produce even a 3 sigma effect, my money is on the possibility that this is really just a statistical fluke. &nbsp;I find it highly unlikely all previous searches would have overlooked multiple supersymmetric (i.e. SUSY) particles and that these particles would only show up in this single isolated channel in such a weak way, despite the high energies of the two experiments. &nbsp;It looks to me like a rifle shot hole in the general exclusion of such particles for almost all other parameters. <div class="blogger-post-footer">Copywrite Andrew Oh-Willeke (2012)</div>andrewhttp://www.blogger.com/profile/08172964121659914379noreply@blogger.com2tag:blogger.com,1999:blog-7315236707728759521.post-81983867245207440272014-06-09T12:24:00.000-06:002014-06-14T13:08:07.165-06:00New Archaic Y-DNA R1b In Southern Siberia?A <a href="https://www.blogger.com/comment.g?blogID=4123559132014627431&amp;postID=312117757237072964&amp;isPopup=true">recent comment at the Eurogenes blog</a> states:<br /><blockquote>"Two out of three afanasievo remains and one okunevo remains tested R1b1 (M269) and one afanasievan – R1b."<br /><br />Source (in russian) : http://pereformat.ru/2014/05/arbins-2/</blockquote>The <a href="http://en.wikipedia.org/wiki/Afanasevo_culture">Afansevo culture</a>, which appears to be the one referred to in the post above:<br /><blockquote>is the earliest Eneolithic archaeological culture found until now in south Siberia, occupying the Minusinsk Basin, Altay and Eastern Kazakhstan.<br /><br />Conventional archaeological understanding tended to date at around 2000–2500 BC. However radiocarbon gave dates as early as 3705 BC on wooden tools and 2874 BC on human remains. The earliest of these dates have now been rejected, giving a date of around 3300 BC for the start of the culture.<br /><br />The culture is mainly known from its inhumations, with the deceased buried in conic or rectangular enclosures, often in a supine position, reminiscent of burials of the Yamna culture, believed to be Indo-European. Settlements have also been discovered. The Afanasevo people became the first food-producers in the area by breeding cattle, horses, and sheep. Metal objects and the presence of wheeled vehicles are documented. These resemblances to the Yamna culture make the Afanasevo culture is a strong candidate to represent the earliest cultural form of a people later called the Tocharians.<br /><br />The culture became known from excavations in the Minusinsk area of the Krasnoyarsk Krai, southern Siberia, but the culture was also widespread in western Mongolia, northern Xinjiang, and eastern and central Kazakhstan, with connections or extensions in Tajikistan and the Aral area.<br /><br />The Afanasevo culture was succeeded by the Andronovo culture as it spread eastwards, and later the Karasuk culture.</blockquote>The link of the Afansevo culture to the Tocharians is made, for example, in J.P. Mallory and Victor H. Mair, <i>The Tarim Mummies: Ancient China and the Mystery of the Earliest Peoples from the West</i> (2000).<br /><br />There are more than a dozen rural Russian villages or settlements called "Okunevo", and presumably the one referenced above is geographically is a Southern Siberian site near the Afansevo finds in a reasonably similar time frame. <br /><br />One way to read the reference is that three out of three Afansevo remains and one set of nearby in time and place Okunevo remains all had Y-DNA haplogroup R1b, with all but one having enough preservation of the ancient DNA to subtype it as R1b (M269), the predominant Western European subclade of R1b, and the other insufficiently preserved to be more specific than an R1b classification generally.<br /><br />Mallory made the case <a href="http://dienekes.blogspot.com/2011/05/on-tocharian-origins.html">in a 2011 talk</a> that R1b was a Tocharian genetic signature based upon West Eurasian Y-DNA haplogroups found in Uyghur populations that were direct successors to and brought about the fall of the Tocharians during a period of Turkic expansion. But, <a href="http://en.wikipedia.org/wiki/Tocharians">ancient Tarim mummy DNA</a> from ca. 1800 BCE, analyzed in 2009 showed uniformly R1a1a Y-DNA haplogroups (citing Li, Chunxiang. "Evidence that a West-East admixed population lived in the Tarim Basin as early as the early Bronze Age". BMC Biology (February 17, 2010)), so any Y-DNA R1b in that population would have to have entered that gene pool sometime in the following 2400 years or so, and was apparently not present initially.<br /><br />This would be very notable as there are no other instances of ancient Y-DNA R1b so far East, particularly in a population strongly presumed to be Indo-European ca. 3300 BCE. <br /><br />There are many ancient Y-DNA samples from Siberia and other parts of the Russian Steppe around that time or a bit later that are overwhelmingly R1a (including ancient Y-DNA from individuals who were part of the <a href="http://en.wikipedia.org/wiki/Andronovo_culture">Andronovo culture</a> that followed the Afansevo culture, suggesting that the later specifically Indo-Iranian culture may have replaced Afansevo, rather than evolving from Afansevo) or have Y-DNA Q, a sister Y-DNA clade to R. &nbsp;But, there are no ancient Y-DNA samples to my knowledge that are consistently R1b or even R1b at all, in that region.<br /><br />Today, R1b-M269 is predominant in large swaths of Western and Northern Europe <a href="http://dienekes.blogspot.com/2014/02/recent-radiation-of-r-m269-males-in.html">where it expanded fairly recently</a> (see, e.g. haplogroup and subhaplogroup mutation rate based age estimates <a href="http://dienekes.blogspot.com/2012/07/on-age-of-y-chromosome-haplogroup-r1b.html">here</a>). It is also found in Armenians, Turks, north Iranians, and Lezgins among others (basically, West Asians).<br /><br />The <a href="http://dienekes.blogspot.com/2012/05/bell-beakers-from-germany-y-haplogroup.html">oldest known ancient Y-DNA R1b sample</a> is from a late Copper Age Bell Beaker culture individual in Germany ca. 2800 BCE to 2000 BCE.<br /><br />Circumstantial evidence and the phylogeny of Y-DNA haplogroup R1 strongly points to an ultimate origin of the haplogroup well to the east of the places where Y-DNA R1b is most common today, but just where has never been pinned down very definitively. <a href="http://dienekes.blogspot.com/2013/11/ancient-dna-from-upper-paleolithic-lake.html">Ma'alta boy</a> with Y-DNA R* from ca. 24,000 years ago around the Altai pushes potential Paleolithic spread of R* far to the East, but triangulations from R2 in South Asia, R1a focused in Central and Eastern Europe into Siberia, and R1b in Western Europe (possibly as a late arrival from what is now Czech territory), has favored an origin around the Caucasus mountains or West Asia or Central Asia with no hint of an Eastward expansion for R1b in recent prehistory.<br /><br />Of course, a mention in a Russian language blog post that I am relying on a second hand translation of, when another Eurogenes commentator doubts the workmanlike quality of the investigators involved, in and of itself, is not exactly authoritative and stinks of mere rumor. But, the rumor is specific and plausible enough (and my cynicism regarding the quality of work done by ancient DNA researchers is not so great) that I think it deserves a mention.<br /><br />I've previous stated, repeatedly, that I believe that R1b in Europe was spread by a linguistically non-Indo-European culture (probably part of the same language family as the modern Basque language) whose speakers only later converted linguistically to Indo-European languages, mostly by proto-Celtic and proto-Germanic populations around and after Bronze Age Collapse ca. 1,200 BCE. Other investigators have argued that R1b was spread by Indo-Europeans, probably quite a bit earlier.<br /><br />If Y-DNA haplogroup R1b was common or even predominant in the Afansevo culture, however, it becomes more plausible both that Afansevo was not Indo-European, and that the peoples who spread R1b in Europe were linguistically Indo-European people who were descended from or historically related to the Afansevo people, although none of this would be definitive.<br /><br />UPDATE: &nbsp;A blog post <a href="http://vaedhya.blogspot.com/2013/07/a-hidden-gem-in-central-asia-previously.html">here</a>&nbsp;from July 13, 2013, analyzing a recent paper on modern Y-DNA distributions in Central Asia that notes R1b-M269 in Turkmen and Uzbek populations of Central Asia (but not in other Central Asian and Siberian populations) that are probably not the product of recent historic flukes, adds useful data points when evaluating these questions. &nbsp;The R1b-M269 in those areas could very plausible have origins in Afansevo populations. &nbsp;Of course, it is still more common in the Caucasus (Armenians, Azeris, Georgians, Ossetians).<div class="blogger-post-footer">Copywrite Andrew Oh-Willeke (2012)</div>andrewhttp://www.blogger.com/profile/08172964121659914379noreply@blogger.com1tag:blogger.com,1999:blog-7315236707728759521.post-65447279777793695472014-06-09T00:57:00.001-06:002014-06-09T01:26:13.217-06:00New Ancient DNA Results Galore<a href="http://dienekes.blogspot.com/2014/06/ancient-dna-from-bronze-age-altai.html">Ancient DNA from the Altai region</a>, often a West Eurasian-East Eurasian border, shows a mix of West Eurasian and East Eurasian genetics in a number of individuals from ca. 2742 BCE to ca. 914 BCE. &nbsp;Uniparental DNA isn't quite so definitive on the existence of admixture, but the autosomal data in every case where it is available, indicates a significant minority of Asian admixture.<br /><br />Another <a href="https://mcidublin.conference-services.net/reports/template/onetextabstract.xml?xsl=template/onetextabstract.xsl&amp;conferenceID=3958&amp;abstractID=814052">large sample of ancient DNA from the Russian Steppe from 1000 BCE to 7000 BCE</a>, shows a major transition from older samples representing typical European hunter-gatherers before 4000 BCE, followed by a transition to a population with significant "Ancestral Northern European" ancestry.<br /><br /><a href="https://mcidublin.conference-services.net/reports/template/onetextabstract.xml?xsl=template/onetextabstract.xsl&amp;conferenceID=3958&amp;abstractID=814309">Another conference paper</a> used maize genetics (some from ancient maize samples) to document the path of diffusion of this New World&nbsp;domesticated crop through the Americas. &nbsp;(Gambler's House, meanwhile, has a <a href="http://gamblershouse.wordpress.com/2014/05/31/the-evidence-from-oral-traditions/">nice post on the light shed by oral history on the ancestry and migration history of the Pueblo people</a> of the American Southwest, addressing difficult issues of how to deal with "legendary history." &nbsp;The migration purportedly starts with a volcanic eruption, tsunami and earthquake to the Southeast of the Four Corners area providing an archaeological recognizable event to search for to corroborate the story.) &nbsp;A <a href="https://mcidublin.conference-services.net/reports/template/onetextabstract.xml?xsl=template/onetextabstract.xsl&amp;conferenceID=3958&amp;abstractID=812201">conference paper using a similar methodology</a> uses the genetics of TB, which appears contrary to earlier conventional wisdom to have pre-Neolithic origins, to track human origins and migrations, which tends to corroborate important outlines of models of human migrations from other sources.<br /><br /><a href="http://www.plosgenetics.org/article/info%3Adoi%2F10.1371%2Fjournal.pgen.1004401">Another new ancient DNA study</a> favors a maritime route via Cyprus and the Aegean, over an Anatolian route for the source of the Neolithic colonists who gave rise to the LBK and CP first wave archaeological cultures:<br /><blockquote>Sixty-three skeletons from the Pre Pottery Neolithic B (PPNB) sites of Tell Halula, Tell Ramad and Dja'de El Mughara dating between 8,700–6,600 cal. B.C. were analyzed, and 15 validated mitochondrial DNA profiles were recovered. In order to estimate the demographic contribution of the first farmers to both Central European and Western Mediterranean Neolithic cultures, haplotype and haplogroup diversities in the PPNB sample were compared using phylogeographic and population genetic analyses to available ancient DNA data from human remains belonging to the Linearbandkeramik-Alföldi Vonaldiszes Kerámia and Cardial/Epicardial cultures. We also searched for possible signatures of the original Neolithic expansion over the modern Near Eastern and South European genetic pools, and tried to infer possible routes of expansion by comparing the obtained results to a database of 60 modern populations from both regions. Comparisons performed among the 3 ancient datasets allowed us to identify K and N-derived mitochondrial DNA haplogroups as potential markers of the Neolithic expansion, whose genetic signature would have reached both the Iberian coasts and the Central European plain. Moreover, the observed genetic affinities between the PPNB samples and the modern populations of Cyprus and Crete seem to suggest that the Neolithic was first introduced into Europe through pioneer seafaring colonization.</blockquote>The study also documents the significant shifts between the Pre Pottery Neolithic population of the Northwestern Fertile Crescent and its current population genetics. &nbsp;On the other hand, one should not read too much into conclusions based on a sample of just 15 ancient mtDNA haplogroup assignments.<div class="blogger-post-footer">Copywrite Andrew Oh-Willeke (2012)</div>andrewhttp://www.blogger.com/profile/08172964121659914379noreply@blogger.com1tag:blogger.com,1999:blog-7315236707728759521.post-12749349697267688772014-06-08T23:24:00.002-06:002014-06-09T00:49:10.636-06:00Neutrino 2014 Offers Nothing No Re Neutrinoless Double Beta Decay Or CosmologyThe recap of cosmology based neutrino data and neutrinoless double beta decay experiments is unchanged from news already reported at this blog.<br /><br /><b>The Cosmology Data</b><br /><br />On the cosmology front, the bottom line state of the art figure after considering all of the outstanding data is is Neff of 3.32 +/- 0.27 (with Neff equal to 3.04 in a case with the three Standard Model neutrinos and neutrinos with masses of 10 eV or more not counting in the calculation), and the sum of the masses of each of the neutrino mass eigenstates is less than 0.28 eV (at the 95% confidence level, and less than 0.2 eV at a 68% confidence level).<br /><br />While the Neff value is not inconsistent with a fourth neutrino species, given the the sum of the three Standard Model neutrino mass eigenstates is not less than about 0.06 eV, this would require that a fourth effective neutrino species have a mass of less than 0.22 eV at the two sigma level and less than 0.14 eV at the one sigma level. <br /><br />Yet, as noted previously, an additional sterile neutrino with a mass of 0.001 to 0.1 eV has been largely ruled out by two separate sets of reactor experiments, leaving a narrow window of 0.1 eV to 0.22 eV for an additional neutrino, despite reactor anomaly data fitting best to a 1 eV additional neutrino species.<br /><br />In short, the cosmology data taken as a whole and in light of everything else we know about neutrinos, disfavors the existence of a light reactor anomaly sterile neutrino that oscillates with the ordinary Standard Model neutrinos. &nbsp;A closing talk at Neutrino 2014 summarized the state of affairs by stating that the dominant 3+1 paradigm is almost ruled out by current experimental data already. &nbsp;An earlier talk <a href="https://indico.fnal.gov/getFile.py/access?contribId=295&amp;sessionId=25&amp;resId=0&amp;materialId=slides&amp;confId=8022">explored these tensions</a>&nbsp;in that data in greater depth.<br /><br /><b>Neutrinoless Double Beta Decay</b><br /><br />Nothing has changed since <a href="http://dispatchesfromturtleisland.blogspot.com/2013/12/gerda-directly-contradicts-heidelberg.html">my last post on neutrinoless double beta decay experiment results in December of 2013</a>. &nbsp;But, the Neutrino 2014 conference in Boston last week did recap the data from the half dozen or so current experiments and the similar number of experiments that will come on line before long.<br /><br />EXO and Kamland report consistent results for the rate of 2vBB decays (which the Standard Model permits) at the 1.4 sigma level.<br /><br />The EXO result is 2.165 +/- 0.0573 * 10^21 years.<br />The Kamland &nbsp;result is 2.32 +/- 0.094 * 10^21 years.<br /><br />These confirmations give us some confidence that the methodology of these experiments are sound, and provides a firm experimental data point from which BSM theories in which it is possible to calculate relative rates of 2vBB decays and 20BB decays can be evaluated. &nbsp;We now know, as the data points below reveal, that neutrinoless double beta decay, if it happens at all, is at least 10,000 times less common than 2vBB decays.<br /><br />The GERDA experiment which rules out neutrinoless beta decay for 2.1*10^25 years at the 90% confidence level is the strongest individual exclusion, followed closely by the <a href="http://arxiv.org/abs/1402.6956">EXO-200</a> and Kamland results. &nbsp;The coefficient in front of 10^25 years at the 90% confidence level for Kamland is 1.9, for CUORICINO is 0.28 and for NEMO-3 is 0.11. &nbsp;The combined exclusion from all data is a bit stronger, but still on the same order of magnitude.<br /><br />These correspond to upper limits on Majorana masses of 0.14 eV to 0.34 eV from the most strict results and 0.33 eV to 0.87 eV from the least strict bounds. &nbsp;Of course, oscillation data put minimum absolute neutrino mass scales for both inverted hierarchies and normal hierarchies well below those levels.<br /><br />Ruling out a completely Majorana mass for neutrinos if there is an inverted hierarchy is something that is "just around the corner" over the next several years with currently planned experiments. &nbsp;Ruling out a completely Majorana mass for neutrinos if there is a normal hierarchy is beyond the scope of neutrinoless double beta decay experiments currently on the drawing board and will take quite a while. &nbsp;Current experiments have detector material masses on the order of 1 ton. &nbsp;An experiment that would rule out completely Majorana mass for a normal neutrino mass hierarchy would require on the order of 1000 tons of material.<br /><br />Also, in many BSM theories, including many SUSY theories, there are sources of neutrinoless double beta decay in addition to those associated with Majorana mass neutrinos. &nbsp;So, as exclusions of neutrinoless double beta decay grow greater over time, the limits on these BSM theories are tightened, even before Majorana mass neutrinos themselves can be ruled out.<br /><br />Glass half full Majorana neutrino advocates would argue that the results so far say little, because current experiments aren't precise enough to detect neutrinoless double beta decay at the predicted frequencies of their theories, even if it exists. &nbsp;Glass half empty skeptics would argue that the absence of any positive evidence of lepton number violation is yet another instance of BSM theories failing to deliver any observable evidence in their favor.<br /><br />More neutrally, in any BSM theory which has both Majorana neutrinos and other sources of neutrinoless double beta decay, the alternative sources can't be more than twice as great as the Majorana sources in an inverted hierarchy and can't be more than about five times as great as the Majorana sources in a normal hierarchy. &nbsp;This cutoff is sufficiently strong to rule out a fair amount of BSM parameter space.<br /><br />Also, it isn't entirely clear that lepton number violation from Majorana mass neutrinos alone is actually sufficient to account for the actual lepton number of the universe which is strongly suspected to have far more antileptons than leptons (the lepton number of the universe is largely a function of the ratio of neutrinos to antineutrinos in the universe and would be extremely close to 1:1 if the lepton number of the universe started out at 0 and there were no lepton number violating processes). &nbsp;If other BSM contributions to lepton number violation and observed neutrinoless double beta decay are not substantial, the question of a non-zero lepton number of the universe (if there is one) remains unsolved.<br /><br />It is also worth noting that there were no other announcements at Neutrino 2014 of any evidence from any other source of lepton number violating processes. &nbsp;Neutrinoless double beta decay also remains the most promising place, given current experimental limitations, to look for lepton number violating processes.<div class="blogger-post-footer">Copywrite Andrew Oh-Willeke (2012)</div>andrewhttp://www.blogger.com/profile/08172964121659914379noreply@blogger.com1tag:blogger.com,1999:blog-7315236707728759521.post-39520352095090812372014-06-05T21:31:00.001-06:002014-06-05T22:13:26.695-06:00Most Northern Hemisphere Men Have Patrilineal Ancestry In SE Asia<blockquote>[W]e genotype 13 new highly informative single-nucleotide polymorphisms in a worldwide sample of 4413 males that carry the derived allele at M526, and reconstruct an NRY haplogroup tree with significantly higher resolution for the major clade within haplogroup K, K-M526.<br /><br />Although K-M526 was previously characterized by a single polytomy of eight major branches, the phylogenetic structure of haplogroup K-M526 is now resolved into four major subclades (K2a–d). The largest of these subclades, K2b, is divided into two clusters: K2b1 and K2b2. K2b1 combines the previously known haplogroups M, S, K-P60 and K-P79, whereas K2b2 comprises haplogroups P and its subhaplogroups Q and R.<br /><br />Interestingly, the monophyletic group formed by haplogroups R and Q, which make up the majority of paternal lineages in Europe, Central Asia and the Americas, represents the only subclade with K2b that is not geographically restricted to Southeast Asia and Oceania. Estimates of the interval times for the branching events between M9 and P295 point to an initial rapid diversification process of K-M526 that likely occurred in Southeast Asia, with subsequent westward expansions of the ancestors of haplogroups R and Q.</blockquote>From Tatiana M Karafet, Fernando L Mendez, Herawati Sudoyo, J Stephen Lansing and Michael F Hammer, "<a href="http://www.nature.com/ejhg/journal/vaop/ncurrent/full/ejhg2014106a.html">Improved phylogenetic resolution and rapid diversification of Y-chromosome haplogroup K-M526 in Southeast Asia</a>", European Journal of Human Geneticas (June 4, 2014).<br /><br /><b>Y-DNA R and Q have origins in SE Asia Probably Between 45 kya and 70 kya.</b><br /><br />The most common Y-DNA haplogroup type in Europe is R (specifically, R1a and R1b), although this distribution probably didn't arise for most of Europe until the second wave of farmer/herder migrations to Europe, a thousand to two thousand years or so after the first farmers brought the Neolithic Revolution to Europe.&nbsp; <br /><br />R1a is associated with Indo-European settlement starting as far back as the Corded Ware culture or earlier in Central to Eastern Europe and Central Europe with ancient DNA evidence of the population's genotype extended all of the way to the Tarim Basin in far Western China at its greatest extent for essentially all of the Bronze Age and into the 7th century CE or so, when Uygur populations emerge in the region.<br /><br />R1b is the predominant Y-DNA haplogroup of Western Europe and a very basal branch of it (R1b-V88) is common among the mostly pastoralist speakers of the Chadic languages in the African Sahel, a branch that probably arrived around 5,200 years ago based on archaeological evidence. &nbsp;A migration probably brought this Y-DNA haplogroup into Western Europe at high frequencies sometime after that, although the precise archaeological culture associated with the predominance of R1b in Western Europe isn't entirely clear. &nbsp;I've advanced that hypothesis that the Bell Beaker culture (the earliest to have R1b ancient DNA discovered so far) was responsible (for lack of any better candidates), but other evidence points to the prior Megalithic culture members who were first farmers in much of Western Europe, but with very fragile evidence, mostly from archaeologically inferred population booms and busts and no ancient DNA at all, to support that hypothesis.<br /><br />Y-DNA haplogroup R2 has a largely South Asian distribution with concentrations highest in the Indus River Valley. Ancient DNA reveals an Y-DNA R* individual, Ma'lta boy ca. 24,000 years ago, with significant autosomal genetic affinity to modern Native Americans near the Altai region of Southern Siberia.<br /><br />Y-DNA haplogroup Q is the most common Y-DNA haplogroup of Native Americans and is also found in Siberia.<br /><br />Thus, the Y-DNA P clade within newly redesignated Y-DNA K2b is the leading Y-DNA clade of the Northern part of the Northern hemisphere. &nbsp;The latest study cited above indicates that the Y-DNA P clade that includes <b>R and Q probably arose in Southeast Asia, coincident with the expansion of Y-DNA K2, in general, and then migrated West together before expanding into their current range, from an intermediate source somewhere in the region from India to Iran to Central Asia.</b><br /><br /><b>More On The Expansion of K2 into SE Asia</b><br /><b><br /></b>Both Y-DNA haplogroup C (whose Asian specific break from other Eurasian Y-DNA haplogroups is more basal than K) and Y-DNA haplogroup P (which is part of K2) haplogroups are found in Australian aboriginal men and indigeneous Papuan peoples. So, the rapid expansion of K2 giving rise to sub-haplogroups had to have taken place before about 45,000 years ago, the earliest securely dated archaeological evidence of modern human presences in those places.<br /><br />It isn't clear if C and K arrived in Southeast Asia in a single migration of a genetically mixed population, or if they were two separate waves of migration that only started to produce a Y-DNA haplogroup mixed population in SE Asia prior to migrations to Australia and Papua New Guinea.<br /><br />Suggestive evidence, but no smoking evidence, suggests that modern humans most likely reached Southeast Asia from South Asia around the time of the Toba volcanic eruption ca. 74,000 years ago. &nbsp;The 74,000 years ago date would also fit an mtDNA mutation rate estimated <a href="http://en.wikipedia.org/wiki/Human_mitochondrial_DNA_haplogroups">expansion of mtDNA haplogroups N and R out of India</a>.<br /><br />This time span (from 45,000 years ago to 74,000 years ago) is long enough to accommodate either a one wave or two wave scenario. &nbsp;Time ranges from 100,000 years ago to about 55,000 years ago could be squared with hypothesis proving interpretations of the archaeological evidence.<br /><br />My weak personal bias is an expectation that these waves of migration were separate, with C expanding first (probably around 74,000 years ago), based mostly upon the phylogeny of the Y-DNA C haplogroup expanded in Asia, which seems to show a rapid "race across the coastal route" path from India that differs quite a bit from the pattern seen in haplogroup K. &nbsp;Haplogroup K2 would then migration to SE Asia in a separate wave perhaps 5,000 to 10,000 years later.<br /><br />Also, sometime between 45,000 and 74,000 years ago, somewhere between India and the island of Flores, these early modern human migrants to Asia admixed with archaic hominins whose Denisovan-like genetic traces are present in modern Australian Aborigines, Melanesians and Phillipino Negrito populations at significant levels. &nbsp;The peak admixture percentage in the source population for these groups is estimated to have been around 8%. &nbsp;My weak personal bias that this admixture took place mostly on the island of Flores with H. Florensis who would have Denisovan DNA in that scenario, but I'm less confident of any particular scenario for Denisovan admixture than I once was, mostly because of (1) possible evidence of a low but non-zero level of mainland Asian Denisovan admixture that is highly diluted but was not eliminated that is unlikely to be due to Melanesian back migration, and (2) physical anthropology and archaeology suggestions that H. Florensis may have been Homo Erectus that evolved to a smaller size due to island dwarfism. &nbsp;But, I have not yet seen really solid evidence of either point.<br /><br />Homo Erectus was the first hominin species to leave Africa and arrived in Asia including South East Asia around 1,800,000 years ago. &nbsp;It isn't clear if Homo Erectus was still in SE Asia at the time and went extinct as part of the same Toba/migration event, or if this hominin species went extinct in the region at an earlier time, because the archaeological record of them more recently than 100,000 years ago is pretty much non-existent. &nbsp;The genetic evidence related to Denisovan admixture, strongly supports the concluding that the Archaic Denisovan admixture seen in modern humans is from a hominin species that probably was not a direct decedent of Asian Homo Erectus. <br /><br />The species with Denisovan genetics might have replaced Homo Erectus before modern humans reached Southeast Asia from South Asia, or might have co-existed with Homo Erectus in Asian until modern humans brought about the extinction of Homo Erectus. &nbsp;In either case, the extinction of Homo Erectus could have happened either directly, via genocide, or indirectly, for example, through impacts on food supply and habitat. &nbsp;An extinction of Homo Erectus entirely, without a strong role in that process from another hominin species, seems unlikely for an archaic hominin species that had already managed to persist for 1,700,000 years or so in Asia. <br /><br />A Toba/modern human migration model of Homo Erectus extinction seems more parsimonious. <br /><br />There is no meaningful archaeological evidence of an intermediate archaic homin species other than Homo Flores (which seems like a poor candidate to wipe out a continent wide Homo Erectus population) apart from Denisovan admixture in the populations mentioned above, but we really don't have much solid evidence one way or the other to discriminate between different models of Homo Erectus extinction.<br /><br /><b>Footnote on Y-DNA Haplogroup D</b><br /><b><br /></b>Y-DNA haplogroup D is the other main Y-DNA haplogroup, in addition to C and K2 that is found in East Eurasia. &nbsp;It is very common in Japan and is also found in a swath of land from the Anadaman Islands, across South Asia to Tibet and into the steppe to the North of Tibet. &nbsp;The Japan v. non-Japan split in the phylogeny is more basal than the splits within each category and is almost complete (i.e. only Japanese D is found in Japan, and only non-Japanese D is found in South Asia).<br /><br />The details of a DE split are controversial and beyond the scope of this post, but the question with Y-DNA haplogroup D is whether its island-like distribution is a result of a much wider range that was split up by subsequent migration, or whether it migrated to Asia after Y-DNA C and K2, perhaps seeking out niches not already occupied by modern humans in Asia ca. 30-40 kya. &nbsp;I tend to favor the later scenario, because there is so little evidence of Y-DNA D anywhere else in Asia, and because the later scenario is still consistent with the evidence on the earliest migrations of modern humans to Japan. &nbsp;I also tend to favor a scenario in which the Japanese Y-DNA D carriers arrive via a Northern route from somewhere North of Tibet, rather than a Southern Coastal route.<br /><br />On the other hand, mutation rate data tend to favor a spit between Y-DNA D and Y-DNA E around the same time as the split between Y-DNA K1 and Y-DNA K2, for which the archaelogically favored date would be around 70,000 years ago, or perhaps a few thousand years earlier. &nbsp;It could be that Y-DNA D expanded on a Northern route from Central Asia to Korea and then trickled down into India and the Andaman Islands from Tibet, prior to the LGM ca. 20,000 years ago, while Y-DNA C and K2 expanded along a Southern route from India into South East Asia, but that the LGM ice age wiped out all but a few relict populations with Y-DNA D, thus breaking up its range.<br /><br />Another factor favoring Y-DNA haplogroup D as a post-Y-DNA C and K2 wave is that none of the Y-DNA haplogroup D populations has any significant non-Neanderthal archaic hominin admixture.<br /><br /><b>The New Y-DNA Haplogroup K1.</b><br /><br />The Y-DNA haplogroups known as L (mostly South Asian and especially the Indus River Valley) and T (geographically broad early Neolithic and/or Epipaleolithic expansion from around Mesopotamia into Europe and parts of Africa and since diluted in many places), have been included in a newly designated Y-DNA K1 haplogroup. <br /><br />It would appear that K1, which stayed in West Eurasia (probably in Iran or South Asia) before it split from K2, which continued on to SE Asia around 70 kya, if not earlier.<br /><br />K1 could also have backmigrated from Southeast Asia around the same time as Y-DNA haplogroups Q and R, but that seems much less likely as there are few traces of Y-DNA haplogroup L or T in Southeast Asia that can't be much more easily explained by later migrations.<br /><br /><br /><br /><br /><br /><div class="blogger-post-footer">Copywrite Andrew Oh-Willeke (2012)</div>andrewhttp://www.blogger.com/profile/08172964121659914379noreply@blogger.com13tag:blogger.com,1999:blog-7315236707728759521.post-57823928828799567532014-06-04T17:20:00.001-06:002014-06-04T17:20:27.999-06:00Forward Backward Top Quark Production Asymmetry GoneAnother once notable potential signal of beyond the Standard Model physics, the forward backward top quark production asymmetry, <a href="http://resonaances.blogspot.com/2014/06/another-one-bites-dust.html">has disappeared</a> as experimental precision has increased, more data has reduced statistical error, and the theoretical prediction has been refined. &nbsp;The data from both Tevatron and the LHC now match the Standard Model prediction.<div class="blogger-post-footer">Copywrite Andrew Oh-Willeke (2012)</div>andrewhttp://www.blogger.com/profile/08172964121659914379noreply@blogger.com0tag:blogger.com,1999:blog-7315236707728759521.post-89639568420686772502014-06-04T16:19:00.000-06:002014-06-04T16:19:05.137-06:00Discovering The Z BosonIn the early 1970s, a few years after my father graduated from Standard with an engineering PhD, while he was working as an associate professor in Georgia Tech in Atlanta, Georgia and was just starting his family, physicists discovered "weak neutral currents".<br /><br />We now understand these phenomena to be mediated by the Z boson of the Standard Model of Particle Physics. &nbsp;At the time, this had been predicted by the Glashow-Salam-Weinberg model that would eventually become the Standard Model, but not yet confirmed experimentally. &nbsp;The 2012 discovery of the Higgs boson provided the finishing touch of experimental confirmation for direct descendant of that model.<br /><br />A&nbsp;<a href="https://indico.fnal.gov/getFile.py/access?contribId=235&amp;sessionId=10&amp;resId=0&amp;materialId=slides&amp;confId=8022">nice introductory talk at the Neutrino 2014 conference</a> in Boston this week, tells the story of what it was like to be a scientist doing the work that led to that discovery back then. &nbsp;The drama, played out with slide rules, electronic punch card mainframe computers, hand written transparencies, and small collaborations recalls stories that I heard when I was growing up from my father about academic life in the STEM fields in the early 1970s.<br /><br />It is remarkably how sophisticated those scientists could be without so many of the fundamental tools used by modern investigators.<div class="blogger-post-footer">Copywrite Andrew Oh-Willeke (2012)</div>andrewhttp://www.blogger.com/profile/08172964121659914379noreply@blogger.com0tag:blogger.com,1999:blog-7315236707728759521.post-68011951023032288032014-06-04T15:49:00.000-06:002014-06-04T19:18:08.692-06:00Degenerate Sterile Neutrino Ruled OutLuboš Motl from The Reference Frame Blog <a href="http://motls.blogspot.com/2014/06/minos-disfavors-nearly-degenerate.html">reports</a> that the U.S. based MINOS experiment has largely ruled out the existence of a sterile neutrino flavor, in addition to the three "fertile" neutrino flavors (i.e. neutrinos that interact via the weak nuclear force which are either lefter handed neutrinos or right handed anti-neutrinos) with a mass nearly degenerate (delta mass squared of 0.01 ev<sup>2</sup> or less which translates into a mass difference of 0.1 eV or less) with the fertile neutrino species.<br /><br />The MINOS results from the <a href="https://indico.fnal.gov/conferenceOtherViews.py?view=standard&amp;confId=8022">Neutrino 2014 conference in Boston</a> have been <a href="http://arxiv.org/pdf/1405.6540.pdf">replicated almost exactly by the Chinese Daya Bay neutrino experiment</a> using similar methods (i.e. a set of several neutrino detectors hundreds of miles from each other and from the reactor neutrino source) which were reported at the same conference. &nbsp;The fact that the conclusions have been simultaneously and independently confirmed gives us considerable confidence that they are correct.<br /><br />Fortunately, the data necessary to measure differences in mass and mixing angles for a fourth or fifth sterile neutrino with the three Standard Model neutrinos in the MINOS and Daya Bay experiments does not impact the determination of Theta 13, the squared mass difference between states one and three, or some of the other key parameters of the model which would complicate the analysis if they were strongly interdependent upon each other in fits of experimental data from these experiments to neutrino oscillation models with sterile neutrinos.<br /><br />According to the new data from MINOS and Daya Bay, any sterile neutrino would have to be either at least 100 meV heavier than the heaviest of the three "fertile neutrinos" or less than 1 meV different in mass from the three fertile neutrinos<br /><br /><b>Background</b><br /><br /><i>The Three Light "Fertile" Neutrinos of the Standard Model</i><br /><br />Multiple experimental sources have confirmed in experiments measuring neutrino oscillations and in cosmology observations, that there are at least the three Standard Model fertile neutrino flavors that have been observed in weak force decays. &nbsp;Precision electroweak data, for example from the LEP experiment, rule out the existence of additional "fertile neutrinos" with a mass of less than 45,000,000 eV.<br /><br />The absolute value of the mass difference between the first and second neutrino mass eigenstates is about 8 meV. The absolute value of the mass difference between the second and third neutrino mass eigenstates is about 50 meV.<br /><br />The sum of the three neutrino mass eigenstates is at least 0.058 eV in a "normal" mass hierarchy, and at least 0.108 in an inverted mass hiearchy. <br /><br />The latest direct experimental measurements reported at Neutrino 2014 merely confirm that the electron neutrino's most favored mass eigenstate has a mass of under <a href="https://indico.fnal.gov/getFile.py/access?contribId=244&amp;sessionId=12&amp;resId=1&amp;materialId=slides&amp;confId=8022">about 0.225 eV</a> (which would imply a sum of the three fertile neutrino mass eigenstates no higher 0.303 eV given the experimentally measured mass differences between these neutrino mass states). &nbsp;The <a href="http://arxiv.org/abs/1403.1544">highest credible prediction</a> that I've seen of this sum of mass states based in theory, which assumes a near degenerate inverted mass hierachy is 0.254 eV. &nbsp;Direct experimental measurements of other flavors of neutrinos add no meaningful insight at all because they are even less precise and absurdly exceed what other well motivated theoretical and observational considerations permit.<br /><br />Thus, the highest possible absolute sum of the three masses is about five times as large as the lowest possible value. &nbsp;The absolute value of the neutrino masses is certainly still an open question, but it has been narrowed to less than a single order of magnitude when measured on a sum of fertile neutrino mass states basis.<br /><br /><i>The Possibility of Light "Reactor Anomaly" Sterile Neutrinos</i><br /><br />The "reactor anomaly" suggest a&nbsp;<a href="http://arxiv.org/pdf/1303.3011.pdf">less than definitive possibility that there is another "sterile neutrino" that oscillates with the three fertile neutrinos</a>. But there are tensions between the various data points suggesting this possibility, particularly between appearance and disappearance data at some reactors, which should be functions of each other. <br /><br />Best fits for reactor anomaly sterile neutrino models have pointed to a single sterile neutrino of about 1 eV or more in rest mass that mixes only infrequently with fertile neutrinos (compared to the rates at which they mix with each other, specifically, for sterile neutrinos of more than 0.1 eV <a href="https://indico.fnal.gov/getFile.py/access?contribId=260&amp;sessionId=17&amp;resId=0&amp;materialId=slides&amp;confId=8022">not more than 2.2% of the time</a>&nbsp;for an electron neutrino). As the Daya Bay pre-print linked earlier in this post explains:<br /><blockquote>At the moment, there are three experimental results from neutrino oscillation experiments, which give hints that sterile neutrinos could exist. These three results, usually referred to as anomalies, are the LSND (and MiniBooNE) anomaly, the Gallium anomaly, and the reactor anomaly, which all point to sterile neutrinos with mass of the order of 1 eV and small mixing. It should be noted that if such sterile neutrinos exist, they could be produced in the early Universe, and have played an important role in the cosmological evolution. Global ﬁts to data from short-baseline neutrino oscillation experiments suggest that the data can be described by either three active and one sterile (3+1) neutrinos or three active and two sterile (3+2) neutrinos. However signiﬁcant constraints come from experiments which would appear to disfavor these anomalies.</blockquote>In general, while the reactor anomaly remains one of the more important unsolved questions in physics at this point, the significance of the data supporting it has declined somewhat over time. &nbsp;One recent study estimated the statistical significance of the reactor anomaly to be <a href="http://dispatchesfromturtleisland.blogspot.com/2014/02/the-reactor-anomaly-might-not-be-real.html">just 1.4 standard deviations</a>. &nbsp;Systemic error and flawed theoretical calculations may account for much of it.<br /><br />Best fits for 1+3+1 models, with one sterile neutrino lighter than any of the three Standard Model neutrinos, and one heavier, suggest a best fit mass of 3.2 eV for the five neutrino flavors combined.<br /><br /><i>Cosmology Data Regarding The Number Of Neutrino Flavors And Their Mass</i><br /><br />Cosmological estimates of the number of effective neutrino species from cosmic background radiation observations and similar data have also pointed, but less than definitively, to the possibility of a light sterile neutrino in addition to the three Standard Model neutrinos.<br /><br />Cosmology measurements favor a combined sum of the three neutrino masses that is less than about 0.3 eV, subject to a number of model dependent considerations (after the final Planck data on that point). &nbsp;A reactor anomaly sterile neutrino is not forbidden by cosmology data on the number of effective neutrino species (Neff) but is disfavored by data on the estimated sum of the masses of the respective neutrino flavors at a value of 1 eV of rest mass, which exceeds best estimates for the sum of all of the neutrino flavor masses combined. &nbsp;Best fits for 1+3+1 models are strongly at odds with cosmology data on the sum of the neutrino masses in all possible flavors.<br /><br />However, it is important to note that neutrinos are defined for cosmology purposes, however, to have masses on the order of 1 eV or less, even if they would be considered neutrinos for other purposes in fundamental physics. &nbsp;So, for example, a 2500 eV sterile neutrino dark matter candidate would not count as a neutrino for cosmology observation purposes. &nbsp;Even a 3.1 eV sterile neutrino pushes the boundaries of what would be considered a neutrino for cosmology model purposes.<br /><br />Cosmology data regarding Neff favor 3+1 models (i.e. a single sterile neutrino models) strongly relative to 3+2 models (i.e. models with two sterile neutrinos), the Chi-square fits to reactor data, given the respective numbers of degrees of freedom in each model, are not substantially improved by using 3+2 models rather than 3+1 models. &nbsp;Reactor data tends to do the same thing, although 1+3+1 models are disfavored far less strongly than 3+2 models.<br /><br /><b>Significance of Findings</b><br /><br />The exclusion of degenerate sterile neutrinos is not unexpected. &nbsp;But, it largely rules out a possibility that experiments without multiple detectors spaced hundreds of miles apart and from a source reactor could not exclude. &nbsp;This allows data from other experiments to be fit to less exotic sterile neutrino parameter spaces that other experiments cannot distinguish themselves, without loss of rigor.<br /><br />A reactor anomaly sterile neutrino mass would be too light to be a warm dark matter or cold dark matter candidate if it is a thermal relic (if it were a thermal relic, it would be "hot dark matter" which is excluded as a explanation for dark matter phenomena experimentally). But, obviously, any experimental evidence for a non-Standard Model fundamental particle, even if it is not definitive, is a big deal.<br /><br />In the end, my prediction is that the reactor anomaly will evaporate as systemic errors and theoretical calculation issues are clarified, eventually ruling out the possibility of a light sterile neutrino. &nbsp;There is too much tension between the weak evidence in favor of sterile neutrinos for it to be likely that it will stand the test of time, and too little theoretical motivation for their existence. &nbsp;But, it is too early to rule their existence out at this point based upon observational evidence alone at this point.<div class="blogger-post-footer">Copywrite Andrew Oh-Willeke (2012)</div>andrewhttp://www.blogger.com/profile/08172964121659914379noreply@blogger.com0