Goldstone boson currents in a kaon condensed color-flavor locked phase

Abstract

We study the stability of the kaon condensed color-flavor locked (CFL) phase of dense quark matter with regard to the formation of a nonzero Goldstone boson current. In the kaon condensed phase there is an electrically charged fermion which becomes gapless near {mu}{sub s}{sup (1)}{approx_equal}1.35{delta} and a neutral fermion which becomes gapless near {mu}{sub s}{sup (2)}{approx_equal}1.61{delta}. Here, {mu}{sub s}=m{sub s}{sup 2}/(2p{sub F}) is the shift in the Fermi energy due to the strange quark mass m{sub s} and {delta} is the gap in the chiral limit. The transition to the gapless phase is continuous at {mu}{sub s}{sup (1)} and first order at {mu}{sub s}{sup (2)}. We find that the magnetic screening masses are real in the regime {mu}{sub s} {mu}{sub s}{sup (2)}. We show that there is a very weak current instability for {mu}{sub s}>{mu}{sub s}{sup (1)} and a more robust instability in a small window near {mu}{sub s}{sup (2)}. We show that in the Goldstone boson current phase all components of the magnetic screening mass are real. There is a range of values of {mu}{sub s} below 2{delta} in which the magnetic gluon screening masses are imaginary but themore » phase is stable with respect to electrically neutral fluctuations of the gauge field.« less