Plasma screening and the critical end point in the QCD phase diagram

Abstract

In heavy-ion collisions, fluctuations of conserved charges are known to be sensitive observables to probe criticality for the QCD phase transition and to locate the position of the putative critical end point (CEP). In this work we seek to show that the Linear Sigma Model with quarks produces an effective description of the QCD phase diagram in which deviations from a Hadron Resonance Gas are due to plasma screening effects, encoded in the contribution of the ring diagrams. Accounting for these, it is possible to include in the description the effect of long-range correlations. To set the model parameters we use LQCD results for the crossover transition at vanishing chemical potential. Finally, studying baryon number fluctuations from the model, we show that the CEP can be located within the HADES and/or the lowest end of the NICA energy domain, √ sNN ∼ 2 GeV.

Particle Ratios in a Multicomponent Nonideal Hadron Resonance Gas

“…It is suggested that the LQCD calculations however cannot be used to directly determine the position of this CEP. The CEP has not yet been found for μ B /T ≤ 2 and 145 ≤ T ≤ 155 MeV [97][98][99]. The results of the search for the CEP and the first-order phase boundary have narrowed the region of interest to collision energies below ffiffiffiffiffiffiffi s NN p = 20 GeV.…”