Cold Nuclear Matter Effects on J/Psi as Constrained by Deuteron-Gold Measurements at sqrt(s_NN) = 200 GeV

TL;DR

This study analyzes J/psi production in deuteron-gold collisions at 200 GeV, revealing cold nuclear matter effects and providing constraints on nuclear shadowing and breakup cross sections, but highlighting the need for further hot matter investigation.

Contribution

It offers updated measurements of cold nuclear matter effects on J/psi production, constraining nuclear shadowing models and breakup cross sections at RHIC energies.

Findings

J/psi suppression increases with rapidity in d+Au collisions.

Breakup cross sections are estimated to be around 2.2-2.8 mb.

Current cold nuclear matter constraints are insufficient to isolate hot matter effects.

Abstract

We present a new analysis of J/psi production yields in deuteron-gold collisions at sqrt(s_NN) = 200 GeV using data taken by the PHENIX experiment in 2003 and previously published in [S.S. Adler et al., Phys. Rev. Lett 96, 012304 (2006)]. The high statistics proton-proton J/psi data taken in 2005 is used to improve the baseline measurement and thus construct updated cold nuclear matter modification factors R_dAu. A suppression of J/psi in cold nuclear matter is observed as one goes forward in rapidity (in the deuteron-going direction), corresponding to a region more sensitive to initial state low-x gluons in the gold nucleus. The measured nuclear modification factors are compared to theoretical calculations of nuclear shadowing to which a J/psi (or precursor) break-up cross-section is added. Breakup cross sections of sigma_breakup = 2.8^[+1.7_-1.4] (2.2^[+1.6_-1.5]) mb are obtained by fitting these calculations to the data using two different models of nuclear shadowing. These breakup cross section values are consistent within large uncertainties with the 4.2 +/- 0.5 mb determined at lower collision energies. Projecting this range of cold nuclear matter effects to copper-copper and gold-gold collisions reveals that the current constraints are not sufficient to firmly quantify the additional hot nuclear matter effect.