Strangeness Excitation Functions and Transition from Baryonic to Mesonic Freeze-Out

TL;DR

This paper analyzes the transition from baryonic to mesonic freeze-out in heavy-ion collisions using the Statistical Model, explaining observed particle ratio peaks and their relation to the hadronic gas phase transition.

Contribution

It demonstrates that the Statistical Model can reproduce key features of particle ratios and identifies the baryon-to-meson transition as the cause of observed deviations.

Findings

Reproduces the Lambda/pi ratio peak with the Statistical Model.

Shows the K+/pi+ ratio change is less pronounced than observed.

Finds particle ratio deviations align with the baryon-to-meson transition.

Abstract

The sharp peak in the K+/pi+ ratio in relativistic heavy-ion collisions is discussed in the framework of the Statistical Model. In this model a rapid change is expected as the hadronic gas undergoes a transition from a baryon-dominated to a meson-dominated gas. The maximum in the Lambda/\pi$ ratio is well reproduced by the Statistical Model, but the change in the K+/pi+ ratio is somewhat less pronounced than the one observed by the NA49 collaboration. The calculated smooth increase of the K-/pi ratio and the shape of the Xi-/pi+ and Omega-/pi+ ratios exhibiting maxima at different incident energies is consistent with the presently available experimental data. We conclude that the measured particle ratios with $20-30%$ deviations agree with a hadronic freeze-out scenario. These deviations seem to occur just in the transition from baryon-dominated to meson-dominated freeze-out.