An Effective Theory for Baryons in the CFL Phase

We study the effective field theory for fermions in the color-flavor locked (CFL) phase of high density QCD. The effective theory contains a flavor nonet of baryons interacting with a nonet of pseudoscalar Goldstone bosons as well as a singlet scalar Goldstone boson. The theory is similar to chiral perturbation theory in the one-baryon sector. We explain how to incorporate quark mass terms and study the spectrum as a function of the strange quark mass. Without meson condensation gapless baryon modes appears if the strange quark mass exceeds a critical value m_s^2/(2p_F)=Delta, where p_F is the Fermi momentum and Delta is the gap in the chiral limit. We show that kaon condensation leads to a rearrangement of the baryon spectrum and shifts the critical strange quark mass for the appearance of a gapless mode to higher values.Comment: 12 pages, 2 figures; corrected Fig. 2; clarified eq.(23

Polarized fermions in the unitarity limit

We consider a polarized Fermi gas in the unitarity limit. Results are calculated analytically up to next-to-leading order in an expansion about d=4 spatial dimensions. We find a first order transition from superfluid to normal phase. The critical chemical potential asymmetry for this phase transition is delta_mu_c= 2/(mu epsilon)*(1-0.467\epsilon), where epsilon=4-d is the expansion parameter and 'mu' is the average chemical potential of the two fermion species. Stability of the superfluid phase in the presence of supercurrents is also studied.Comment: 5 pages, 5 figures, LaTeX2e; minor changes, note added at the end, to be published in PR

CFL Phase of High Density QCD at Non Zero Strange Quark Mass

We compute free energy of quark matter at asymptotically high baryon number density in the presence of non zero strange quark mass including dynamics of pseudo Nambu-Goldstone bosons due to chiral symmetry breaking, extending previously existing analysis based on perturbative expansion in $m_s^2/4\mu\Delta.$ We demonstrate that the CFL$K^0$ state has lower free energy than the symmetric CFL state for $0<m_s^2/4\mu\Delta<2/3$. We also calculate the spectrum of the fermionic quasiparticle excitations about the kaon condensed ground state in the regime $m_s^2/4\mu\Delta \sim 1$ and find that $(m_s^2/4\mu\Delta)_{crit}=2/3$ for the CFL-gCFL phase transition, the leading order result reported in [1], is not modified.Comment: 16 pages, 3 figure