Baryon resonances in a chiral hadronic model for the QCD equation of state

In this paper we study the influence of hadronic resonances on the phase diagram calculated with an effective chiral flavor SU(3) model. We show that varying the couplings of the baryonic resonances to the attractive scalar and the repulsive vector fields has a major impact on the order and location of the chiral phase transition and the possible existence of a critical end point, as well as on the thermodynamic properties of the model. Furthermore, we study (strange) quark number fluctuations and show the related susceptibilities both at zero baryochemical potential and when crossing the phase transition line at three different points in the T-mu plane. We obtain the best agreement with current lattice data if we choose a rather strong vector coupling, which in our model limits the phase transition to a smooth crossover and implies the nonexistence of a critical end point.