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 ${\mu }_q$.

Comments: Lattice2002(nonzerot). 3 pages Latex, 3 Postscript figures. Talk presented at Lattice 2002, MIT, Cambridge, Massachusetts, 24-29 June 2002