High Density Quark Matter under Stress

We study the effect of SU(3) flavor breaking on high density quark matter. We discuss, in particular, the effect a non-zero electron chemical potential and a finite strange quark mass. We argue that these perturbations trigger pion or kaon condensation. The critical chemical potential behaves as $\mu_e\sim\sqrt{m m_s} \Delta/p_F$ and the critical strange quark mass as $m_s \sim m^{1/3} \Delta^{2/3}$, where $m$ is the light quark mass, $\Delta$ is the gap, and $p_F$ is the Fermi momentum. We note that parametrically, both the critical $\mu_e$ and $m_s^2/(2p_F)$ are much smaller than the gap.