J/psi production at high transverse momentum in p+p and Cu+Cu collisions at \sNN=200GeV

TL;DR

This paper reports measurements of J/psi production at high transverse momentum in proton-proton and copper-copper collisions at 200 GeV, showing that at high pT, J/psi production scales with binary collisions, unlike at lower pT.

Contribution

First measurement of high pT J/psi production in Cu+Cu collisions at RHIC, demonstrating binary scaling and estimating B-meson decay contributions.

Findings

J/psi production at high pT scales with binary collisions in Cu+Cu.

Suppression observed at lower pT is not present at high pT.

B-meson decay contributes approximately 13% to J/psi production.

Abstract

The STAR collaboration at RHIC presents measurements of \Jpsi$\to{e^+e^-}$ at mid-rapidity and high transverse momentum ($p_T>5$ GeV/$c$) in \pp and central \cucu collisions at \sNN = 200 GeV. The inclusive \Jpsi production cross section for \cucu collisions is found to be consistent at high $p_T$ with the binary collision-scaled cross section for \pp collisions, in contrast to previous measurements at lower $p_T$, where a suppression of \Jpsi production is observed relative to the expectation from binary scaling. Azimuthal correlations of $J/\psi$ with charged hadrons in \pp collisions provide an estimate of the contribution of $B$-meson decays to \Jpsi production of $13% \pm 5%$.