3-flavour lattice QCD at finite density and temperature: QCD at finite isospin density revisited

We simulate 3-flavour lattice QCD at finite temperature and isospin chemical potential $\mu_I$. In particular we study the nature of the finite temperature transition for quark masses close to the critical mass at which this transition for zero chemical potentials changes from a first order transition to a crossover. We find that the Binder cumulants, used to determine the position of this transition, have very strong dt dependence. This leads us to an estimate of the critical mass which is about 20% below previous estimates. In addition, when this dt dependence is taken into account, we find that the Binder cumulants show very little dependence on mu_I. From this we conclude that we do not as yet see any evidence for the expected critical endpoint. We have argued previously that the position and nature of the finite temperature transition for small mu_I should be the same as that for small quark-number chemical potential mu.