Bjorken initial energy density estimation in Xe-Xe collisions at $\sqrt{s_{NN}}=5.44$ TeV using ALICE

Abstract

The Bjorken initial energy density (${ϵ}_B$) has been estimated in different centrality classes in Xe-Xe collisions using Bjorken formula. Three different cases have been considered. In Case I, we have fixed the formation time (${\tau }_0$) and varied the area of overlap region ($A_{overlap}$). In Case II, we have fixed both ${\tau }_0$ and $A_{overlap}$ and we have varied both ${\tau }_0$ and $A_{overlap}$ in Case III. We observed that the ${ϵ}_B$ is first increasing and then decreasing while going from central to peripheral collisions in Case I whereas it is decreasing in Case II and III, as expected. The ${ϵ}_B$ value for top central and mid central collisions in Case II and for all centrality classes in Case III are greater than 1 $GeV/(fm{)}^3$, indicating the possibility of QGP medium formation respectively. The ${ϵ}_B$ results of the Pb-Pb at $\sqrt{s_{NN}}=2.76$ and 5.02 TeV are compared. In Case II, it is observed that in the centrality class (0-5)%, the ${ϵ}_B$ value in Xe-Xe collisions at $\sqrt{s_{NN}}=5.44$ TeV is 34.66% less than in Pb-Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV and 57.12% less than at 5.02 TeV. This may be interpreted as, the system size in Xe-Xe collisions at $\sqrt{s_{NN}}=5.44$ TeV is 34.66% smaller than in Pb-Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV and 57.12% smaller than at 5.02 TeV. Similarly in Case III in the centrality class (0-5)%, the ${ϵ}_B$ value in Xe-Xe collisions at $\sqrt{s_{NN}}=5.44$ TeV is 3.22% more than in Pb-Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV and 32.18% less than at 5.02 TeV. This may be interpreted as, the system size in Xe-Xe collisions at $\sqrt{s_{NN}}=5.44$ TeV is 3.22% bigger than in Pb-Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV and 32.18% smaller than at 5.02 TeV. The results obtained in the Case III seems more suitable than Case II.

Comments: 09 pages, 11 figures