Exploring the QGP phase in high multiplicity pp and A-A collisions using Color String Percolation Model at LHC energies

May 16, 2022, 4:30 PM


Aditya Nath Mishra (Wigner Research Centre for Physics Budapest, Hungary)


We have analyzed the transverse momentum spectra of charged particles in high multiplicity pp collisions at LHC energies 5.02 and 13 TeV using the Color String Percolation Model (CSPM). For heavy ions, Pb-Pb at 2.76 and 5.02 TeV along with Xe-Xe at 5.44 TeV have been analyzed. The initial temperature is extracted both in low and high multiplicity events in pp collisions. For heavy-ion collisions, the temperature is obtained as a function of centrality. Universal scaling in the temperature from pp and A − A collisions is obtained when multiplicity is scaled by the transverse interaction area. For the higher multiplicity events in pp collisions at 5.02 and 13 TeV, the initial temperature is above the universal hadronization temperature and is consistent with the creation of deconfined matter. From the measured
energy density ε and the temperature, the dimensionless quantity ε/T4 is obtained. Our results agree with the Lattice Quantum Chromo Dynamics simulations (LQCD) up to ∼210 MeV and beyond that there is a sharp increase in ε/T4, reaching the ideal gas of quarks and gluons value of ε/T4 = 16 at temperature ∼ 230 MeV. It has been argued that there exists a three-phase structure of matter in QCD: hadronic matter, a plasma of deconfined massive quarks and a plasma of massless quarks and gluons with full-color deconfinement and chiral symmetry restoration. Our results suggest that chiral symmetry restoration occurs at a temperature
∼210 MeV.

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