Multiplicity dependent behavior of thermodynamic parameters in proton–proton collisions at 13 TeV

We analyze transverse momentum spectra of identified particles produced in proton–proton collisions at 13 TeV using the thermodynamically consistent Tsallis distribution. Both the freezeout volume ($V$) and the effective temperature ($T$) are extracted. The energy density ($\varepsilon$), particle number density ($n$), pressure ($P$), squared sound speed ($c_s^2$), and entropy density ($s$) are among the other thermodynamic quantities that are computed. The aforementioned parameters are presented in relation to the multiplicity class and are expected to decrease as the multiplicity class increases. The squared speed of sound decreases gradually in the first few multiplicity classes, and then it decreases sharply. Besides, different particles are observed to have different freezeout surfaces, but all particles are seen to have the same thermalization. Furthermore, we displayed the correlations between the various parameters, all showing positive correlations. There is a sudden change in the correlations of the non-dimensionless parameter ($\varepsilon /T^4$) and $T$, $〈d{N}_{ch}/d\eta 〉$ and $T$, and $〈d{N}_{ch}/d\eta 〉$ and $c_s^2$, which may show the phase transition from hadronic matter to quark–gluon plasma (QGP). The result of the correlation between $c_s^2$ and $T$ is close to the Lattice Quantum Chromodynamic (LQCD) prediction.