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

TL;DR

This study analyzes high-energy proton-proton and heavy-ion collisions at the LHC using the Color String Percolation Model to explore the quark-gluon plasma phase above the deconfinement temperature, revealing universal scaling and thermodynamic properties.

Contribution

It introduces a unified analysis of $pp$ and $A-A$ collisions at LHC energies, extracting temperature and energy density, and demonstrating universal scaling and the onset of QGP phase.

Findings

Universal temperature scaling across collision types.

Sharp increase in energy density ratio above 210 MeV.

Evidence of quark-gluon plasma formation at high temperatures.

Abstract

In the present work we have analyzed the transverse momentum spectra of charged particles in high multiplicity ${\it pp}$ 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 ${\it pp}$ 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 $\bm \varepsilon$ and the temperature the dimensionless quantity $\bm \varepsilon/T^{4}$ is obtained. Our results for Pb-Pb and Xe-Xe collisions show a sharp increase in $\bm \varepsilon/T^{4}$ above T $\sim$ 210 MeV and reaching the ideal gas of quarks and gluons value of $\bm \varepsilon/T^{4} \sim$ 16 at temperature $\sim $ 230 MeV. In case of $pp$ collisions only $\bm \varepsilon/T^{4} \sim $ 10 corresponding to $\sim$ 30 degrees of freedom.