Phase structure of four flavor QCD in the T μ plane from a new method for simulations of lattice gauge theories at non zero baryon density

We review a method for numerical simulations of lattice gauge theories at non-zero baryonic chemical potential we recently proposed. We first report on a test of the method using a solvable model and then present results for the phase structure of four flavour QCD. For the first time the region of chemical potential up to 1.4 T_C is explored, finding a first order transition line.