Centrality and System Size Dependence among Freezeout Parameters and the Implications for EOS and QGP in High-Energy Collisions

Utilizing the Modified Hagedorn function with embedded flow, we analyze the transverse momenta ((Formula presented.)) and transverse mass ((Formula presented.)) spectra of (Formula presented.) in Au–Au, Cu–Cu, and d–Au collisions at (Formula presented.) = 200 GeV across various centrality bins. Our study reveals the centrality and system size dependence of key freezeout parameters, including kinetic freezeout temperature (Formula presented.), transverse flow velocity (Formula presented.), entropy-related parameter (Formula presented.), and kinetic freezeout volume (V). Specifically, (Formula presented.) and n increase from central to peripheral collisions, while (Formula presented.) and V show the opposite trend. These parameters also exhibit system size dependence; (Formula presented.) and (Formula presented.) are smaller in larger collision systems, whereas V is larger. Importantly, central collisions correspond to a stiffer Equation of State (EOS), characterized by larger (Formula presented.) and smaller (Formula presented.), while peripheral collisions indicate a softer EOS. These insights are crucial for understanding the properties of Quark–Gluon Plasma (QGP) and offer valuable constraints for Quantum Chromodynamics (QCD) models at high temperatures and densities.