Probing thermalization and system size effect on a hadron resonance gas for hydrodynamical study of hadronic phase

The study of matter prevailed in the microsecond old early universe has been made possible with the help of accelerators by colliding hadrons and nuclei at relativistic energies. Thus the study of this particular phase in the evolution of hot QCD matter is critical. In this respect, the Excluded Volume Hadron Resonance Gas (EVHRG) model has been highly successful. It has also been shown that the effect of different collision energies can be introduced by appropriately chosen baryochemical potentials (µ_B). In this article, we use the EVHRG model with the inclusion of Hagedorn states for heavier masses to observe the effect of varying collision energies on the speed of sound (c²_s) and Knudsen number (Kn) of a hadron gas. The effect of system size on Knudsen number is also explored explicitly