Pion and kaon condensation at finite temperature and density

Abstract

In this paper, we study $O(2N)$-symmetric ${\ensuremath{\phi}}^{4}$-theory at finite temperature and density using the two-particle irreducible $1/N$ expansion. As specific examples, we consider pion condensation at finite isospin chemical potential and kaon condensation at finite chemical potential for hypercharge and isospin charge. We calculate the phase diagrams and the quasiparticle masses for pions and kaons in the large-$N$ limit. It is shown that the effective potential and the gap equation can be renormalized by using local counterterms for the coupling constant and mass parameter, which are independent of temperature and chemical potentials.