On the critical endpoint and the first‐order phase transition in the extended Polyakov Nambu Jona‐Lasinio Lagrangian

The (Polyakov) Nambu‐ Jona‐Lasinio (PNJL) approach is an effective theory for low energies which shares with Quantumchromodynamics (QCD) the global symmetries. This approach is easy to handle and allows for analytical results for many of the observables which are of interest for the studies of ultrarelativistic heavy‐ion collisions but also for the merger and collisions of neutron stars. It allows in particular to study the density and temperature dependence of quark masses and of the masses of mesons and baryons as well as the chiral phase transition. In recent times, this transition came in the focus of interest because it is expected that the upcoming experiments at the Fair (Germany) and NICA (Russia) facilities will observe a Quark‐Gluon‐Plasma (QGP) at finite baryon chemical potential. In this contribution, we show that the extended PNJL model is able to describe the properties of symmetric matter at vanishing chemical potential, as determined by lQCD calculations.