Pi0 -> Gamma Gamma in Dense QCD

Abstract

QCD superconductors in the color-flavor-locked (CFL) phase support light excitations (generalized pions) in the form of particle-particle or hole-hole excitations. We analyze the generalized process ${\tilde{\pi }}^0\to \tilde{\gamma }\tilde{\gamma }$ in the weak coupling limit and show that it is related to the recently suggested Wess-Zumino-Witten (WZW) term. In dense QCD, the radiative decay of the generalized pion is constrained by geometry and vanishes at large density.

Comments: 7 pages, 1 figure