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

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.