Observation of different scenarios in different temperatures in small and large collision systems

Abstract

We used the modified Hagedron function and analyzed the experimental data measured by the BRAHMS, STAR, PHENIX and ALICE Collaborations in Copper-Copper, Gold-Gold, deuteron-Gold, Lead-Lead, proton-Lead and proton-proton collisions, and extracted the related parameters (kinetic freeze-out temperature, transverse flow velocity, kinetic freeze-out volume, mean transverse momentum and initial temperature) from the transverse momentum spectra of the particles (non-strange and strange particles). We observed that all the above parameters decrease from central to peripheral collisions, except transverse flow velocity which remains unchanged from central to peripheral collisions. The kinetic freeze-out temperature depends on the cross-section interaction of the particle such that larger cross-section of the particle corresponds to smaller T0, and reveals the two kinetic freeze-out scenario, while the initial temperature depends on the mass of the particle and it increase with the particle mass. The transverse flow velocity and mean transverse momentum depends on the mass of the particle and the former decrease while the later increase with the particle mass. In addition, the kinetic kinetic freeze-out volume also decrease with particle mass which reveals the volume differential freeze-out scenario and indicates different freeze-out surfaces for different particles. We also extracted the entropy index-parameter n and the parameter N0, and the former remains almost unchanged while the later decrease from central to peripheral collisions. Furthermore, the kinetic freeze-out temperature, transverse flow velocity, kinetic freeze-out volume, initial temperature, mean transverse momentum and the parameter N0 at LHC are larger than that of RHIC, and they show their dependence on the collision cross-section as well as on collision energy at RHIC and LHC.

Analyses of pp, Cu–Cu, Au–Au and Pb–Pb Collisions by Tsallis-Pareto Type Function at RHIC and LHC Energies

“…One can see that T is slightly larger in the central collisions compared to the peripheral collisions because there is a large number of participants in the former, which makes the reaction very intense, and thus more energy is stored in the former. These results validate our recent results [ 16 , 18 , 48 , 49 ]. In addition, T in collisions are also shown, which is slightly lower than or approximately equal to that in peripheral collisions at the same center of mass energy.…”

“…The present work is a continuation of our work published in [ 16 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 ] using different statistical fit functions to extract parameters relevant to the collective properties of the hadronic medium.…”

“…However, other studies [ 9 , 10 ] claim that the decoupling of the particles depends on their mass such that massive particles decouple early from the system. In other works [ 11 , 12 , 13 , 14 , 15 , 16 ], the decoupling scenarios of different particles are different, including the single decoupling scenario in which all particles are decoupled at the same time, the double-decoupling scenario in which strange and nonstrange particles are decoupled separately, and each particle’s multiple decoupling scenarios for decoupling from the system, respectively. This is an open question up to now in the community.…”