Identified charged antiparticle to particle ratios near midrapidity in Cu+Cu collisions at sqrt(s) = 62.4 and 200 GeV

TL;DR

This study measures antiparticle to particle ratios for protons, kaons, and pions in Cu+Cu collisions at 62.4 and 200 GeV, finding little dependence on collision centrality and system size, and comparing results across different energies and systems.

Contribution

It provides the first detailed analysis of antiparticle to particle ratios in Cu+Cu collisions at these energies, highlighting the weak influence of system size on chemical freeze-out properties.

Findings

Antiparticle to particle ratios show no strong centrality dependence.

Ratios at 200 GeV agree with those in heavier and lighter systems.

System size has minimal impact on midrapidity chemical freeze-out conditions.

Abstract

Antiparticle to particle ratios for identified protons, kaons and pions at sqrt(s) = 62.4 and 200 GeV in Cu+Cu collisions are presented as a function of centrality for the midrapidity region of 0.2 < eta < 1.4. No strong dependence on centrality is observed. For the <pbar>/<p> ratio at <p_T> ~ 0.51 GeV/c, we observe an average value of 0.50 +/- 0.003_(stat) +/- 0.04_(syst) and 0.77 +/- 0.008_(stat) +/- 0.05_(syst) for the 10% most central collisions of 62.4 and 200 GeV Cu+Cu, respectively. The values for all three particle species measured at sqrt(s) = 200 GeV are in agreement within systematic uncertainties with that seen in both heavier and lighter systems measured at the same RHIC energy. This indicates that system size does not appear to play a strong role in determining the midrapidity chemical freeze-out properties affecting the antiparticle to particle ratios of the three most abundant particle species produced in these collisions.