Towards the chiral critical surface of QCD Original Research Article

The critical endpoint of the QCD phase diagram is usually expected to belong to the chiral critical surface, i.e. the surface of second order transitions bounding the region of first order chiral phase transitions for small quark masses in the {mu,d,ms,μ} parameter space. For μ=0, QCD with physical quark masses is known to be an analytic crossover, requiring the region of chiral transitions to expand with μ for a critical endpoint to exist. Instead, on coarse Nt=4 lattices, we find the area of chiral transitions to shrink with μ, which excludes a chiral critical point for QCD at moderate chemical potentials View the MathML source. First results on finer Nt=6 lattices indicate a curvature of the critical surface consistent with zero and unchanged conclusions.