Abstract:In a system of quark matter we study the chiral phase transition, the behavior of the chiral and quark number susceptibility and the CEP at nite temperature and chemical potential. This is done within the framework of two-avor Nambu and Jona-Lasinio model. We have calculated the chiral quark condensate and the quark number density and, with this, we have found the phase transition type. With these quantities we have determined the phase diagram for QCD and the CEP.

Working in the SU(2) flavor version of the NJL model, we study the effect of taking a finite system volume on a strongly interacting system of quarks, and, in particular, the location of the chiral phase transition and the CEP. We consider two shapes for the volume, spherical and cubic regions with different sizes and different boundary conditions. To analyze the QCD phase diagram, we use a novel criterion to study the crossover zone. A comparison between the results obtained from the two different shapes and several boundary conditions is carried out. We use the method of Multiple Reflection Expansion to determine the density of states and three kinds of boundary conditions over the cubic shape. These boundary conditions are: periodic, anti-periodic and stationary boundary conditions on the quark fields.