KAON CONDENSATION IN NUCLEAR STAR MATTER

The critical density for kaon condensation in ''nuclearstar'' matter is computed up to two-loop order in medium (corresponding to next-to-next-to-leading order in chiral perturbation in free space) with a heavy-baryon effective chiral Lagrangian whose parameters are determined from KN scattering and kaonic atom data. To the order considered, the kaon self-energy has highly non-linear density dependence in dense matter. We find that the four-Fermi interaction terms in the chiral Lagrangian play an important role in triggering condensation, predicting for ''natural'' values of the four-Fermi interactions a rather low critical density, rho(c) < 4rho0.