"Kaon Condensation and Quark-Antiquark Condensate in Dense Matter"

In the framework of a chiral quark model we study $s$-wave $K^-$ condensation with the use of a formalism that goes beyond the linear-density approximation commonly employed in the literature. We find that the linear-density approximation is likely to be valid up to the density $\rho\sim 4\rho_0$, where $\rho_0$ is the normal nuclear matter density, and the critical density $\rho_c^K$ for $\Km$ condensation is estimated to be $\rho_c^K \sim (3-4)\rho_0$. We also investigate the influence on the quark-antiquark condensates of the spontaneous breaking of isospin symmetry associated with $\Km$ condensation. The presence of a $\Km$ condensate is found to suppress the ${\bar{u}}u$ condensate, but the ${\bar{d}}d$ condensate remains unaffected up to the chiral order under consideration. We discuss the implication of the suppressed ${\bar{u}}u$ condensate for chiral symmetry restoration in dense matter.