The rapidity dependence of the proton-to-pion ratio in Au+Au and p+p collisions at sqrt(sNN) = 62.4 and 200 GeV

TL;DR

This study measures proton-to-pion ratios in Au+Au and p+p collisions at different energies and rapidities, revealing energy and rapidity dependence, model comparisons, and a crossing point at high pseudorapidity.

Contribution

It provides new measurements of p/pi ratios across a wide rapidity range and collision energies, highlighting their dependence on energy, rapidity, and collision centrality.

Findings

p/pi ratios are similar at different energies at specific rapidities.

A crossing point of p/pi ratios occurs at eta ~ 3.2 for different collision types.

Model predictions are compared with experimental data.

Abstract

The BRAHMS measured proton-to-pion ratios in Au+Au and p+p collisions at \rootsnn{62.4} and \rootsnn{200} are presented as a function of transverse momentum and collision centrality within the pseudo-rapidity range 0 < eta < 3.8 The results for Au+Au at sqrt(sNN) = 200 GeV are compared with predictions from models which incorporate hydro-dynamics, hadron rescattering and jet production, in the eta interval covered. In Au+Au collisions at sqrt(sNN) = 200 GeV, eta ~ 2.2, and at sqrt(sNN) = 62.4 GeV, eta = 0, the bulk medium can be characterized by the common value of \mi_B ~ 65 MeV. The p/pi ratios measured for these two selections display a striking agreement in the pT range covered (up to 2.2 GeV/c). At a collision energy of 62.4 GeV and at forward pseudo-rapidity we found a crossing point of p/pi+ ratios measured in central and semi-peripheral Au+Au and in p+p reactions. The crossing occurs in the narrow eta bin around value of 3.2, simultaneously in the whole covered pT range (0.3 GeV/c < pT < 2 GeV/c).