Thermal freeze-out parameters and pseudo-entropy from charged hadron spectra in high energy collisions

TL;DR

This study analyzes charged hadron spectra from high-energy collisions using a modified Tsallis-Pareto function to extract thermal freeze-out parameters and introduce a new pseudo-entropy measure, revealing changes in collision mechanisms around 7.7 GeV.

Contribution

It introduces a novel approach using a modified Tsallis-Pareto function with multiple convolutions to fit hadron spectra and defines a new pseudo-entropy to study collision dynamics.

Findings

Parameters change rapidly below 7.7 GeV and slowly above it.

Collision mechanisms vary significantly around 7.7 GeV.

The method effectively describes the spectra across a wide energy range.

Abstract

We collected the transverse momentum (mass) spectra of charged hadrons ($\pi^{-}$, $\pi^{+}$, $K^{-}$, $K^{+}$, $\overline{p}$, and $p$) produced in collisions over a center-of-mass energy range from 2.70 to 200 GeV (per nucleon pair). The modified Tsallis--Pareto-type function (the TP-like function) with average transverse flow velocity is used to describe the contribution of participant or constituent quarks to transverse momentum of considered hadron. The experimental spectra of $\pi^{\mp}$ and $K^{\mp}$ (or $\overline{p}$ and $p$) are fitted by the convolution of two (or three) TP-like functions due to the fact that two (or three) constituent quarks are regarded as two (or three) energy resources in the formation of considered hadron. From the reasonable fits to the spectra, the thermal freeze-out parameters are extracted, and the pseudo-entropy is newly defined and extracted. Some parameters quickly change in the energy range of less than 7.7 GeV, and slowly change in the energy range of greater than 7.7 GeV, indicating the variation of collision mechanism at around 7.7 GeV.