QCD phase diagram constructed with effective models

Abstract

In this work, we obtain a representation of the QCD phase diagram with the help of two effective models, MIT based bag models to describe quark matter and QHD based models to describe hadronic matter. To obtain the phase transition line, we use the Gibbs conditions that determine the critical chemical potential for symmetric matter at zero and finite temperature.

QCD phase diagrams via QHD and MIT based models

“…As for the influence of the different parametrizations of the QHD based model, we can see that the eL3ωρ parametrization always results in higher chemical potentials, and, as the NL3 * ωρ is a stiffer EoS, we conclude the same as already noticed in [51], a stiffer hadron EoS results in a lower chemical potential.…”

“…The same is true when we compare the results for different values of G V , as higher values of G V result in higher values for µ max and also increase the stiffness of the EoS, the same behaviour found in symmetric matter. The increase of the bag pressure value B 1/4 0 also results in higher values of µ max , but it softens the EoS, as we already pointed out in [51] for symmetric matter. So, to summarize, stiffer quark EoSs always favor the hadron phase, unless we change the value of the Bag constant B 1/4 0 and then the opposite is true, a softer quark EoS favors the hadron phase.…”

“…This happens because we choose the values of T 0 exactly to satisfy the restrain imposed by the LQCD and freeze-out results, which states that the temperatures at very low chemical potentials should be around T = 168 MeV. In [51] we have already verified that the maximum temperature obtained depends only on the bag pressure value: the higher the B 1/4 , the higher the maximum temperature. The same conclusion can be drawn here because B(T ) 1/4 has more or less the same value, namely, around 205 MeV, at the maximum temperature for both parametrizations.…”

“…1, and so, as the condition for phase transition when using only the MIT bag model is P = 0, it comes with no surprise that this results are very much alike. The same is true when we use a bag pressure value with no dependence on the temperature, as done in [51]. Now we look at the region of the diagrams at high chemical potentials, i.e., T → 0.…”

“…As for the bag pressure value, we choose a temperaturedependent bag model in order to be able to obtain higher transition temperatures at low chemical potentials and at the same time maintain the transition chemical potentials at low temperatures within a certain range. More details on this discussion can be seen in [15] and [51]. So, the B in Eq.…”