Analyzing transverse momentum spectra by a new method in high-energy collisions

TL;DR

This paper introduces a new Monte Carlo method to analyze transverse momentum spectra of various particles in high-energy nucleus-nucleus collisions, revealing energy-dependent changes in reaction mechanisms.

Contribution

A novel approach modeling particle transverse momentum as a superposition of two participant partons with a modified Tsallis distribution, applied across a wide energy range.

Findings

Effective temperature increases with collision energy.

A boundary around 5 GeV indicates a change in reaction mechanism.

Model agrees well with experimental data.

Abstract

We analyzed the transverse momentum spectra of positively and negatively charged pions ($\pi^+$ and $\pi^-$), positively and negatively charged kaons ($K^+$ and $K^-$), protons and antiprotons ($p$ and $\bar p$), as well as $\phi$ produced in mid-(pseudo)rapidity region in central nucleus--nucleus (AA) collisions over a center-of-mass energy range from 2.16 to 2760 GeV per nucleon pair. The transverse momentum of the considered particle is regarded as the joint contribution of two participant partons which obey the modified Tsallis-like transverse momentum distribution and have random azimuths in superposition. The calculation of transverse momentum distribution of particles is performed by the Monte Carlo method and compared with the experimental data measured by international collaborations. The excitation functions of effective temperature and other parameters are obtained in the considered energy range. With the increase of collision energy, the effective temperature parameter increases quickly and then slowly. The boundary appears at around 5 GeV, which means the change of reaction mechanism and/or generated matter.