SU($4$) Polyakov linear-sigma model at finite temperature and density
  In mean-field approximation, the SU($4$) Polyakov linear - sigma model (PLSM) is constructed in order to characterize the quark-hadron phase structure in a wide range of temperatures and densities. The chiral condensates $\sigma_l$, $\sigma_s$ and $\sigma_c$ for light, strange and charm quarks, respectively, and the deconfinement order-parameters $\phi$ and $\phi^*$ shall be analyzed at finite temperatures and densities. We conclude that the critical temperatures corresponding to charm condensates are greater than that to strange and light ones, respectively. Thus, the charm condensates are likely not affected by the QCD phase transition. Furthermore, increasing the chemical potentials decreases the corresponding critical temperatures. 
Abdel Magied Diab (Egyptian Ctr. Theor. Phys., Cairo, WLCAPP, Cairo),   Azar I. Ahmadov (Baku State U.), Abdel Nasser Tawfik...
nucl-th hep-th