Gluon-photon mixing in dense QCD

Abstract

At high baryonic density with the formation of a diquark condensate Δ≠0, the QCD color symmetry is spontaneously broken. Being massive by the Anderson-Higgs mechanism, a gluon and photon should mix together within two linear combinations due to the color nonconservation. Consequently a gluon G̃ could decay into an e-e+ pair via its photon component. With a low invariant mass (about a few ten MeV) and an extremely narrow width peaking above the continuum background, the purely leptonic decay of a strongly interacting gluon G̃→e-+e+ constitutes a very distinctive signature of the color superconductivity phase. By a similar scenario of gluon-Z mixing, another "missing-energy" decay into invisible neutrinos Ḡ→v+v̄ could arise; its amplitude is, however, (Δ/MZ)2 power suppressed. © 2001 The American Physical Society.