q/qbar->photon is part of Drell Yan, so it's kinematically allowed. Is this somehow related to the difference in speed phenomenologically between a strong and a weak decay? As in is this annihilation what a strong decay means in this case?
Additionally, should a q/qbar pair necessarily be able to annihilate? If they form a color-anitcolor pair, they should be allowed to go to a photon, but otherwise, shouldn't they need to go into a gluon of the appropriate color preserving flavor? Should we expect q/qbar -> gluon to occur ~2x as frequently in proton-antiproton collisions due to this color preserving argument?
