Rapidity and centrality dependence of particle production for identified hadrons in Cu+Cu collisions at $\sqrt{s_{NN}} = 200$ GeV

TL;DR

This study measures identified hadron spectra in Cu+Cu collisions at 200 GeV, revealing how centrality and rapidity influence particle production, collective flow, and suppression effects consistent with jet quenching and nuclear shadowing.

Contribution

It provides detailed measurements of identified hadron spectra at different rapidities and centralities, highlighting the interplay of jet quenching, flow, and initial state effects in heavy-ion collisions.

Findings

Radial flow increases with collision centrality.

Pion and kaon suppression at high transverse momentum is observed and consistent with jet quenching.

Proton-to-meson ratio increases with centrality and is largest at forward rapidity.

Abstract

The BRAHMS collaboration has measured transverse momentum spectra of pions, kaons, protons and antiprotons at rapidities 0 and 3 for Cu+Cu collisions at $\sqrt{s_{NN}} = 200$ GeV. As the collisions become more central the collective radial flow increases while the temperature of kinetic freeze-out decreases. The temperature is lower and the radial flow weaker at forward rapidity. Pion and kaon yields with transverse momenta between 1.5 and 2.5 GeV/c are suppressed for central collisions relative to scaled $p+p$ collisions. This suppression, which increases as the collisions become more central is consistent with jet quenching models and is also present with comparable magnitude at forward rapidity. At such rapidities initial state effects may also be present and persistence of the meson suppression to high rapidity may reflect a combination of jet quenching and nuclear shadowing. The ratio of protons to mesons increases as the collisions become more central and is largest at forward rapidities.