Lattice QCD at finite isospin chemical potential and temperature

Abstract

We simulate lattice QCD at a finite chemical potential $\mu_I$ for isospin ($I_3$) at zero and finite temperatures. At some $\mu_I=\mu_c$ QCD has a second order transition with mean-field critical exponents to a state where ($I_3$) is broken spontaneously by a charged pion condensate. Heating the system with $\mu_I > \mu_c$ we find there is some temperature at which this condensate evaporates. This transition appears to be second order and mean-field at lower $\mu_I$ values, and first order for $\mu_I$ sufficiently large. We are determining the dependence of the finite temperature crossover $T_c$ on $\mu_I$ for $\mu_I < \mu_c$. This is expected to be identical to $T_c$'s dependence on quark-number chemical potential $\mu_q$ for small $\mu_q$.