Centrality evolution of transverse momentum spectra of primary charged particles produced in high-energy Pb+Pb collisions at the LHC
Abstract
Evolution of the experimental mid(pseudo)rapidity [Formula: see text] distributions of primary charged particles with changing collision centrality, measured by the ALICE collaboration in the long [Formula: see text] range (up to [Formula: see text]) in [Formula: see text] collisions at [Formula: see text] and 5.02[Formula: see text]TeV, has been analyzed using thermodynamically consistent Tsallis function with embedded transverse flow. The results have been compared with the earlier results coming from simultaneous analysis of short [Formula: see text] range (up to [Formula: see text]) of [Formula: see text] spectra of the charged pions and kaons, protons and antiprotons in [Formula: see text] collisions at [Formula: see text] and 5.02[Formula: see text]TeV at the LHC. Transverse flow has been absent at low [Formula: see text] values and it starts emerging between collision centralities (40–50)% and (30–40)% in [Formula: see text] collisions at [Formula: see text] and between collision centralities (50–60)% and (40–50)% in [Formula: see text] collisions at [Formula: see text]. Kinetic freeze-out temperature, [Formula: see text], has decreased greatly between collision centralities (40–50)% and (30–40)% in [Formula: see text] collisions at [Formula: see text] and between collision centralities (50–60)% and (40–50)% in [Formula: see text] collisions at [Formula: see text]. We have estimated border value of collision centrality for crossover phase transition from the dense hadronic state to that of QGP state (or mixed state of QGP and hadrons) to be [Formula: see text] and [Formula: see text] in [Formula: see text] collisions at [Formula: see text] and 5.02[Formula: see text]TeV, respectively. Non-extensivity parameter q has decreased systematically with increasing [Formula: see text] and [Formula: see text] (with an increase in collision centrality) in both [Formula: see text] collisions at [Formula: see text] and 5.02[Formula: see text]TeV. This denotes systematic increase in degree of system thermalization with increasing centrality of [Formula: see text] collisions at [Formula: see text] and 5.02[Formula: see text]TeV at the LHC, in agreement with similar result of previous works. Strong negative correlation has been obtained between parameter q and [Formula: see text] as well as between parameter q and [Formula: see text] with Pearson correlation coefficient [Formula: see text] in both [Formula: see text] collisions at [Formula: see text] and 5.02[Formula: see text]TeV. Kinetic freeze-out temperature parameter, [Formula: see text], has proved to be strongly anticorrelated with average transverse flow velocity, [Formula: see text], with [Formula: see text] in both [Formula: see text] collisions at [Formula: see text] and 5.02[Formula: see text]TeV, in agreement with analogous result of earlier works. The obtained results have been compared with those extracted in minimum bias [Formula: see text] and [Formula: see text] collisions at [Formula: see text] and 5.02[Formula: see text]TeV.