In 2013, the LHCb experiment measured the delta-A-CP of this particle to be nonzero. It's not the bottom quark, but this particle is just massive enough to be flavor-tagged since its jets don't mix into the QCD background. X(3872) is posited to be a heavy resonance state of this particle, and the standard model Higgs boson decays into one of these and its anti-particle 2.5% of the time. The existence of this particle was posited as a means of suppressing certain flavor-changing neutral currents in K meson decays via the GIM mechanism, and it was previously posited to exist by looking at approximate invariance under SU(4) symmetry by Bjorken and Glashow. D mesons (*) all contain this particle, which has a mass of 1.2
In 2013, the LHCb experiment measured the delta-A-CP of this particle to be nonzero. It's not the bottom quark, but this particle is just massive enough to be flavor-tagged since its jets don't mix into the QCD background. X(3872) is posited to be a heavy resonance state of this particle, and the standard model Higgs boson decays into one of these and its anti-particle 2.5% of the time. The existence of this particle was posited as a means of suppressing certain flavor-changing neutral currents in K meson decays via the GIM mechanism, and it was previously posited to exist by looking at approximate invariance under SU(4) symmetry by Bjorken and Glashow. D mesons (*) all contain this particle, which has a mass of 1.29 GeV. The existence of this particle was confirmed by finding a resonance at 3.09 GeV at both SLAC and BNL; that simultaneous discovery won Samuel Ting and Burton Richter the Nobel Prize and was called the November Revolution. The J/psi particle is a bound state of this particle and its antiparticle. For 10 points, name this particle, which along with the strange quark makes up the second quark generation.
In 2013, the LHCb experiment measured the delta-A-CP of this particle to be nonzero.
charm quark [accept J/psi before mention]