Exploring the QGP phase above the deconfinement temperature in $pp$ and $A-A$ collisions at LHC energies

Abstract

In the present work we have analyzed the transverse momentum spectra of charged particles in high multiplicity $pp$ collisions at LHC energies $\sqrt{s}=$ 5.02 and 13 TeV published by the ALICE Collaboration using the Color String Percolation Model (CSPM). For heavy ions Pb-Pb at $\sqrt{s_{NN}}=$ 2.76 and 5.02 TeV along with Xe-Xe at $\sqrt{s_{NN}}=$ 5.44 TeV have been analyzed. The initial temperature is extracted both in low and high multiplicity events in $pp$ collisions. For $A-A$ collisions the temperature is obtained as a function of centrality. A universal scaling in the temperature from $pp$ and $A-A$ collisions is obtained when multiplicity is scaled by the transverse interaction area.From the measured energy density $\mathbf{\epsilon }$ and the temperature the dimensionless quantity $\mathbf{\epsilon }/T^4$ is obtained. Our results for Pb-Pb and Xe-Xe collisions show a sharp increase in $\mathbf{\epsilon }/T^4$ above T $\sim$ 210 MeV and reaching the ideal gas of quarks and gluons value of $\mathbf{\epsilon }/T^4\sim$ 16 at temperature $\sim$ 230 MeV. In case of $pp$ collisions only $\mathbf{\epsilon }/T^4\sim$ 10 corresponding to $\sim$ 30 degrees of freedom.

18 pages, 13 figures. arXiv admin note: text overlap with arXiv:2006.10169