Evaluation of kinetic freeze-out properties in different relativistic heavy-ion collision systems at \(\sqrt{s_{NN}}=200\) GeV

Abstract

We present our analysis of the identified hadrons (\(\pi ^+\), \(K^+\), and p) kinetic freeze-out properties in relativistic collisions at \(\sqrt{s_{NN}} = 200\) GeV. We analyze the transverse momentum spectra of these hadrons across various collision systems, such as copper–copper (\(Cu-Cu\)), zirconium–zirconium (\(Zr-Zr\)), ruthenium–ruthenium (\(Ru-Ru\)), uranium–uranium (\(U-U\)), and gold–gold (\(Au-Au\)) collisions, in distinct centrality intervals at the same center-of-mass energy using the modified Hagedorn model with embedded flow. The freeze-out parameters, namely the kinetic freeze-out temperature (\(T_0\)), transverse flow velocity (\(\beta _T\)), and the entropy-related parameter (n), are extracted. Taking \(T_0\) and \(\beta _T\) as common, it is observed that in all the above collisions, \(T_0\), \(\beta _T\), and the parameter n diminish toward the periphery and are greater in central collisions. However, \(T_0\) in central collisions across all the systems remains unchanged, indicating a phase transition from hadronic matter to quark–gluon plasma. Furthermore, the temperature required for the phase transition across various systems is different. Large systems exhibit a shift in the potential start of the phase transition in peripheral collisions, which is intriguing. We also observe a direct relation between the extracted parameters and the system’s size.