Series representation; Pade' approximants and critical behavior in QCD at nonzero T and $mu_B$

Abstract

We discuss the analytic continuation beyond $μ/T \simeq 1$ in QCD at nonzero T and $μ$ by use of the Pade' approximants. The slope of the critical line obtained in this way increases at large $μ$ with respect to the second order Taylor result.In the hot phase Pade' and Taylor approximants coincide, suggesting a very large, and possibly infinite, radius of convergence of the Taylor series in this thermodynamic region.