The Parity-Doublet Model for Strongly-interacting matter

`Within the framework of an improved flavour SU(3) chiral mean-field (CMF) effective model, with parameters constrained by realistic nuclear-matter ground-state properties, the QCD phase diagram is investigated vis-a-vis, the effect of the intermingling between the crossovers corresponding to the nuclear liquid-gas (LG) and the chiral/deconfinement phase transitions. It is observed that the LG transition has considerable effects on the fluctuations of the system, manifest in the beam-energy dependence of its baryon-number cumulants; for matter with isospin-symmetry and zero net strangeness chemical potential. For isospin-asymmetric matter, the model is successfully modified to produce symmetry energy and slope parameter values in agreement with experimental astrophysical constraints. Furthermore, in conjunction with the Tolmann-Oppenheimer-Volkoff equations, the model Equation of State (EoS) is found to result in a maximum mass, and radius, neutron star consistent with the most recent observations. For a non-zero net strangeness chemical potential, the phase diagram is revealed to be modified, such that the chiral/deconfinement phase boundary becomes a smooth crossover for all temperatures and baryo-chemical potentials. Dynamical simulations of heavy-ion collisions are undertaken with the help of the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) model, using the CMF model EoS, to produce results in accordance with currently available di-lepton data from the HADES experiment at GSI.