A pion and one of these particles should result from proton decay, and their appearance under normal circumstances will immediately result in the creation of a photon with 511 keV of energy.  
One of these particles exchanges a virtual photon with an electron in Bhabha scattering, and along with a neutrino, one of these is a side product of the creation of deuterium in the proton-proton chain.  A pion and one of these particles should result from proton decay, and their appearance under normal circumstances will immediately result in the creation of a photon with 511 keV of energy.  They were first postulated as negative energy solutions to a namesake wave equation by Paul Dirac, and they were discovered in 1932 by Carl Anderson.  For 10 points, name this spin-1/2 particle with positive charge, the antiparticle of the electron.
One of these particles exchanges a virtual photon with an electron in Bhabha scattering, and along with a neutrino, one of these is a side product of the creation of deuterium in the proton-proton chain.  
positrons [accept beta-plus particle; accept antielectron before "electron" is read]