Rapidity dependent $K/\pi$ ratios in Au+Au collisions at $\sqrt{s_{NN}}$ = 62.4 GeV

TL;DR

This study measures how the ratio of charged kaons to pions varies with rapidity in gold-gold collisions at 62.4 GeV, revealing a universal dependence on the antiproton/proton ratio and testing theoretical models' accuracy.

Contribution

It provides the first detailed analysis of rapidity-dependent $K/$ ratios at this energy, highlighting limitations of current models at forward rapidities.

Findings

$K/\pi$ ratios at different rapidities align when plotted against $ar{p}/p$ ratio.

Models like UrQMD and AMPT describe mid-rapidity data well but not forward rapidity ratios.

The $K/\pi$ ratio dependence suggests a universal behavior related to baryo-chemical potential.

Abstract

We report on measurements of identified particle yields from Au-Au collisions at $\sqrt{s_{NN}} = 62.4$ GeV made with the BRAHMS spectrometer. Here we will concentrate on the charged $K/\pi$ ratios as function of rapidity and baryo-chemical potential. We find that the $K/\pi$ ratios measured at different rapidities in the analysed dataset have a common dependence with the same ratios measured in mid-rapidity at SPS energies when plotted as function of the $\bar{p}/p$ ratio. The theoretical models used for comparison, UrQMD and AMPT, give a reasonable description of the particle yields at mid-rapidity but fail to do so for the $K/\pi$ ratios at forward rapidity.