Spectra and femtoscopic scales in a hydrokinetic model for baryon-rich fireballs

TL;DR

This paper extends a hydrokinetic model to lower energies with baryon-rich matter, analyzing pion and kaon spectra and interferometry radii in Pb+Pb collisions, showing good agreement at higher energies but some discrepancies at lower energies.

Contribution

It introduces a two-phase equation of state with baryon-rich matter into the hydrokinetic model for lower collision energies, enhancing its applicability.

Findings

Good agreement with experimental radii at 158 AGeV

Discrepancies in radii and ratios at 40 AGeV

Model successfully incorporates phase transition effects

Abstract

The hydrokinetic model and the scheme of dynamical freeze out proposed earlier for the RHIC energy are extended to lower colliding energy for non-vanishing baryon chemical potential. In this case a new two-phase equation of state is applied where baryon-rich hadronic matter is described within modified relativistic mean-field theory. As an example, the approach is employed for analyzing pion and kaon spectra and interferometry radii of Pb+Pb collisions at laboratory energies 40 and 158 AGeV. A good agreement is observed for the transverse mass dependence of the longitudinal radius for both energies studied. The transverse radii $R_{out}, R_{side}$ reproduce experiment at $E_{lab}=$158\ AGeV but at $E_{lab}=$40\ AGeV there is a marked (20 \%) difference from experimental points. This discrepancy is more noticeable in analysis of the ratio $R_{out}/R_{side}$. Nevertheless, considered examples of application of the hydrokinetic model with equation of state including the first order phase transition are quite successful and further development of the model is required.