The effective QCD phase diagram and the critical end point

We study the QCD phase diagram on the temperature T and quark chemical potential mu plane, modeling the strong interactions with the linear sigma model coupled to quarks. The phase transition line is found from the effective potential at finite T and mu taking into account the plasma screening effects. We find the location of the critical end point (CEP) to be (mu(CEP)/T-c, T-CEP/T-c) similar to (1.2, 0.8), where T-c is the (pseudo)critical temperature for the crossover phase transition at vanishing mu. This location lies within the region found by lattice inspired calculations. The results show that in the linear sigma model, the CEP's location in the phase diagram is expectedly determined solely through chiral symmetry breaking. The same is likely to be true for all other models which do not exhibit confinement, provided the proper treatment of the plasma infrared properties for the description of chiral symmetry restoration is implemented. Similarly, we also expect these corrections to be substantially relevant in the QCD phase diagram. (C) 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license.