Major progress has been made in the search for the fundamental properties of strongly interacting matter under extreme conditions by facilities like the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). The formation and description of the Quark-Gluon Plasma (QGP), the deconfined state of quarks and gluons, which is thought to have existed microseconds following the Big Bang is one of their major goals. Though the main method of producing QGP is through high energy heavy-ion collisions, high multiplicity proton- proton (pp) interactions also exhibit some signatures for QGP production.
The QGP phase is short-lived, only lasting approximately up to 10-23 seconds. Therefore, the direct observation of QGP via detectors is impossible. Thus, it is necessary to obtain information on its evolution and freeze-out properties based on the final-state hadrons. In this work, transverse momentum (pT) spectra of identified hadrons produced in both nucleus-nucleus (A − A) and proton-proton (pp) collisions are analysed with the help of different statistical and hydrodynamical models, including the Tsallis distribution, standard distribution (in its multi-component form), and the Blast-Wave model.
Based on the fits of the pT spectra, researchers can determine the necessary thermodynamic and collective parameters, such as the effective temperature, the kinetic freeze-out temperature, the initial temperature, the non-extensivity parameter, the transverse flow velocity, the system volume, the mean transverse momentum, etc. Systematic behaviour of these parameters as functions of collision energy, centrality, and pseudorapidity provides profound information about the evolution of the system and the potential phase transition between hadronic and partonic (QCD) matter. This detailed study leads to a better perception of the freeze-out processes and the complicated nature of the QGP formation in high energy nuclear reactions.