Excitation Functions of Tsallis-like Parameters in High-Energy Nucleus-Nucleus Collisions

TL;DR

This paper analyzes transverse momentum spectra in high-energy nucleus-nucleus collisions using a two-parton Tsallis-like model, revealing excitation functions of freeze-out temperature and flow velocity with a notable plateau from 10 to 200 GeV.

Contribution

It introduces a two-parton Tsallis-like model to describe particle spectra and extracts excitation functions of key collision parameters across energies.

Findings

Kinetic freeze-out temperature increases rapidly then plateaus between 10 and 200 GeV.

Transverse flow velocity also increases with collision energy.

The model fits experimental data well across a wide energy range.

Abstract

The transverse momentum spectra of charged pions, kaons, and protons produced at mid-rapidity in central nucleus-nucleus (AA) collisions at high energies are analyzed by considering particles to be created from two participant partons which are assumed to be contributors from the collision system. Each participant (contributor) parton is assumed to contribute to the transverse momentum by a Tsallis-like function. The contributions of the two participant partons are regarded as the two components of transverse momentum of the identified particle. The experimental data measured in high-energy AA collisions by international collaborations are studied. The excitation functions of kinetic freeze-out temperature and transverse flow velocity are extracted. The two parameters increase quickly from $\approx3$ to $\approx10$ GeV (exactly from 2.7 to 7.7 GeV) and then slowly at above 10 GeV with the increase of collision energy. In particular, there is a plateau from near 10 GeV to 200 GeV in the excitation function of kinetic freeze-out temperature.