# Phenomenology of light- and strange-quark simultaneous production at high energies

## TL;DR

This paper extends a model to describe how light and strange quark phase-space occupancy factors vary with collision energy, revealing a non-monotonic behavior and emphasizing the importance of fitting multiple particle yields for accurate determination.

## Contribution

It introduces an extended phenomenological model for quark occupancy factors that better captures their energy dependence and improves particle ratio predictions.

## Key findings

- $oldsymbol{ ext{Occupancy factors }oldsymbol{\gamma_{q,s}}$ show a non-monotonic energy dependence.
- The model accurately reproduces various particle ratios across energies.
- Fitting multiple particle yields is essential for reliable occupancy factor determination.

## Abstract

This letter presents an extension of EPL116(2017)62001 to light- and strange-quark nonequilibrium chemical phase-space occupancy factors ($\gamma_{q,s}$). The resulting damped trigonometric functionalities relating $\gamma_{q,s}$ to the nucleon-nucleon center-of-mass energies $(\sqrt{s_{NN}})$ looks very similar except different coefficients. The phenomenology of the resulting $\gamma_{q,s}(\sqrt{s_{NN}})$ describes a rapid decrease at $\sqrt{s_{NN}}\lesssim7~$GeV followed by a faster increase up to $\sim20~$GeV. Then, both $\gamma_{q,s}$ become nonsensitive to $\sqrt{s_{NN}}$. Although these differ from $\gamma_{s}(\sqrt{s_{NN}})$ obtained at $\gamma_q(\sqrt{s_{NN}})=1$, various particle ratios including $\mathrm{K}^+/\pi^+$, $\mathrm{K}^-/\pi^-$, $\mathrm{\Lambda}/\pi^-$, $\bar{\mathrm{\Lambda}}/\pi^-$, $\mathrm{\Xi}^+/\pi^+$, and $\mathrm{\Omega}/\pi^-$, can well be reproduced, as well. We conclude that $\gamma_{q,s}(\sqrt{s_{NN}})$ should be instead determined from fits of various particle yields and ratios but not merely from fits to the particle ratio $\mathrm{K}^+/\pi^+$.