Collision energy dependence of the critical end point from baryon number fluctuations in the Linear Sigma Model with quarks

TL;DR

This paper uses the Linear Sigma Model with quarks to explore the QCD phase diagram, emphasizing plasma screening effects and predicting the critical end point's location based on baryon fluctuations, relevant for low-energy heavy-ion collisions.

Contribution

It introduces plasma screening effects into the Linear Sigma Model, providing a more accurate description of the QCD phase diagram and the critical end point location.

Findings

The model predicts the CEP at collision energies around 2 GeV.

Inclusion of plasma screening alters the phase transition characteristics.

The results suggest the CEP is accessible in low-energy heavy-ion experiments.

Abstract

We show that the Linear Sigma Model with quarks produces an effective description of the QCD phase diagram and of the system's equilibrium distribution properties that deviate from those of the Hadron Resonance Gas Model. The deviation is due to the inclusion of plasma screening properties, encoded in the contribution of the ring diagrams and thus to the introduction of a key feature of plasmas near phase transitions, namely, long-range correlations. After fixing the model parameters using input from LQCD for the crossover transition at vanishing chemical potential, we study the location of the Critical End Point in the effective QCD phase diagram. We use the model to study baryon number fluctuations and show that in heavy-ion collisions, the CEP can be located for collision energies $\sqrt{s_{NN}}\sim 2$ GeV, namely, in the lowest NICA or within the HADES energy domain.