Initial and final state temperature of K∗0 in Beam Energy Scan of Au–Au collisions at RHIC energies

To determine the center of mass energy at which ordinary matter undergoes a transition to hot and dense matter, we employed a combination of the blast wave model and Tsallis statistics. Specifically, we analyzed the transverse momentum spectra of resonance particles (in this case, K^∗0) produced in different centrality intervals during Au–Au collisions at various energies ranging from s_NN=7.7 to 39 GeV. Our findings include the phase transition from hadronic matter to the quark-gluon plasma (QGP), and a quick expansion of the system at higher energies and in more central collisions, and disclose the fact that the central collision system, as well as the systems with higher center of mass energies, are easy to be in equilibrium. Our observations indicate a phase transition occurring from ordinary hadronic matter to the quark-gluon plasma (QGP) state in the final stages of collisions but not in the initial stages. Besides, we presented the correlation of T₀ with various parameters and reported the higher excitation degree of the fireball and its rapid expansion. Our results can provide further insights into the role of the fluctuations in thermal excitation and collective expansion.