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

High Energy Physics - Phenomenology 2025-08-18 v2 High Energy Physics - Experiment

Abstract

The Bjorken initial energy density (ϵB\epsilon_{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 (τ0\tau_{0}) and varied the area of overlap region (AoverlapA_{overlap}). In Case II, we have fixed both τ0\tau_{0} and AoverlapA_{overlap} and we have varied both τ0\tau_{0} and AoverlapA_{overlap} in Case III. We observed that the ϵB\epsilon_{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 ϵB\epsilon_{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)3GeV/(fm)^{3}, indicating the possibility of QGP medium formation respectively. The ϵB\epsilon_{B} results of the Pb-Pb at sNN=2.76\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 ϵB\epsilon_{B} value in Xe-Xe collisions at sNN=5.44\sqrt{s_{NN}} = 5.44 TeV is 34.66% less than in Pb-Pb collisions at sNN=2.76\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 sNN=5.44\sqrt{s_{NN}} = 5.44 TeV is 34.66% smaller than in Pb-Pb collisions at sNN=2.76\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 ϵB\epsilon_{B} value in Xe-Xe collisions at sNN=5.44\sqrt{s_{NN}} = 5.44 TeV is 3.22% more than in Pb-Pb collisions at sNN=2.76\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 sNN=5.44\sqrt{s_{NN}} = 5.44 TeV is 3.22% bigger than in Pb-Pb collisions at sNN=2.76\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.

Keywords

Cite

@article{arxiv.2508.08843,
  title  = {Bjorken initial energy density estimation in Xe-Xe collisions at $\sqrt{s_{NN}} = 5.44$ TeV using ALICE},
  author = {Mohammad Asif Bhat and Akankshya Nayak and P. K. Sahu},
  journal= {arXiv preprint arXiv:2508.08843},
  year   = {2025}
}

Comments

09 pages, 11 figures