Collective expansion in pp collisions using the Tsallis statistics

Abstract

We investigate the transverse momentum ($p_{\mathrm{T}}$) spectra of identified hadrons in minimum-bias proton-proton (pp) collisions at a centre-of-mass energy ($\sqrt{s}$) of 0.9, 2.76, 5.02, 7 and 13 TeV in the framework of Tsallis-blast wave (TBW) model. It is found that the model describes well the particle spectra up to 10 GeV/c. The radial flow ($⟨\beta ⟩$) increases with the collision energy. The degrees of non-equilibrium ($q$) and the Tsallis temperature parameter ($T$) show a similar behaviour, but with a much weaker trend. With this dependence of the freeze-out parameters on the collision energy, we evaluate $⟨\beta ⟩$, $T$ and $q$ in pp collisions at $\sqrt{s}=$ 8 and 14 TeV and predict the particle spectra at these two energies. Moreover, in order to investigate the multiplicity dependence of the freeze-out parameters, the TBW model is extended to the spectra at different charged-particle multiplicity classes in pp collisions at $\sqrt{s}=$ 7 and 13 TeV. It is observed that at both energies the radial flow increases with the multiplicity while the degree of non-equilibrium shows an opposite behaviour, which is similar to that observed in proton-nucleus (pA) and nucleus-nucleus (AA) collisions at the Large Hadron Collider (LHC) energies. However, the Tsallis temperature parameter increases with the multiplicity, which is opposite to the trend in pA and AA collisions. At similar multiplicities, the radial flow in pp collisions is stronger than those in pA and AA collisions, indicating that the size of the colliding system has significant effects on the final state particle dynamics. Finally, we apply an additional flow correction to the Tsallis temperature parameter and find that the doppler-corrected temperature parameter almost scales with the multiplicity in a uniform way, despite the difference in the colliding system and collision energy.

13 pages, 9 figures, 6 tables

References in corpus (10)

• Systematic Measurements of Identified Particle Spectra in pp, d+Au and Au+Au Collisions from STAR
• From QCD-based hard-scattering to nonextensive statistical mechanical descriptions of transverse momentum spectra in high-energy $pp$ and $p\bar{p}$ collisions
• Description of High-Energy pp Collisions Using Tsallis Thermodynamics: Transverse Momentum and Rapidity Distributions
• Nuclear modification factors of phi mesons in d+Au, Cu+Cu and Au+Au collisions at sqrt(S_NN)=200 GeV
• An overview of the experimental study of quark-gluon matter in high-energy nucleus-nucleus collisions
• Production of pions, kaons, (anti-)protons and $\varphi$ mesons in Xe-Xe collisions at $\sqrt{s_{\mathrm{NN}}}=5.44$ TeV
• Nonequilibrium kinetic freeze-out properties in relativistic heavy ion collisions from energies employed at the RHIC beam energy scan to those available at the LHC
• Identified particle spectra in Pb-Pb, Xe-Xe and p-Pb collisions with Tsallis blast-wave model
• Using local nuclear scaling of initial condition parameters to improve the system size dependence of transport model descriptions of nuclear collisions
• Centrality and transverse momentum dependence of hadrons in Pb+Pb collisions at LHC

Cited by in corpus (6)

• Investigating the soft and hard limits in transverse momentum spectra in pp collisions
• Hadron transverse momentum distributions in the Tsallis statistics with escort probabilities
• Non-extensive (3+1)-dimensional hydrodynamics for relativistic heavy-ion collisions
• How far can we see back in time in high-energy collisions using charm hadrons?
• QCD phase transition at finite temperature and chemical potential with the non-extensive statistics
• Revisiting the soft-hard separation in the transverse momentum spectra of $pp$ collisions