Transport model study of the $m_T$-scaling for $\Lambda$, K, and $\pi$ HBT-correlations

TL;DR

This study uses the UrQMD transport model to analyze HBT correlations of pions, kaons, and lambdas in heavy ion collisions, showing that incorporating a specific equation of state improves the $m_T$-scaling agreement.

Contribution

It demonstrates that including a soft equation of state with momentum dependence and density-dependent potentials enhances the $m_T$-scaling of HBT radii in transport model simulations.

Findings

HBT radii follow $m_T$-scaling with the modified model.

Cascade mode alone does not reproduce $m_T$-scaling at high energies.

Inclusion of SM-EoS and density-dependent potentials improves agreement.

Abstract

Based on the microscopic transport model UrQMD in which hadronic and string degrees of freedom are employed, the HBT parameters in the longitudinal co-moving system are investigated for charged pion and kaon, and $\Lambda$ sources in heavy ion collisions (HICs) at SPS and RHIC energies. In the Cascade mode, $R_O$ and the $R_L$ at high SPS and RHIC energies do not follow the $m_T$-scaling, however, after considering a soft equation of state with momentum dependence (SM-EoS) for formed baryons and a density-dependent Skyrme-like potential for ``pre-formed'' particles, the HBT radii of pions and kaons and even those of $\Lambda$s with large transverse momenta follow the $m_T$-scaling function $R=3/\sqrt{m_T}$ fairly well.