Measurements of ${\rm Y}$ Production and Nuclear Modification Factor at STAR

Abstract

Thermal suppression of quarkonium production in heavy-ion collisions, due to Debye screening of the quark-antiquark potential, has been proposed as a clear signature of Quark-Gluon Plasma (QGP) formation. At RHIC energies, the ${\rm Y}$ meson is a clean probe of the early system due to negligible levels of enhancement from \bbbar recombination and non-thermal suppression from co-mover absorption. We report on our measurement of the ${\rm Y}\to e^{+}{e}^{-}$ cross section in Au+Au collisions at $\sqrt{s_{NN}}$=200 GeV. We compute the Nuclear Modification Factor by comparing these results to new p+p measurements from 2009 (21 pb${}^{-1}$ in 2009 compared to 7.9 pb${}^{-1}$ in 2006). In order to have a complete assessment of both hot and cold nuclear matter effects on Upsilon production we also report on results from d+Au collisions.

Hard Probes 2012 Proceedings. 4 pages, 4 figures

References in corpus (2)

• Heavy flavor in heavy-ion collisions at RHIC and RHIC II
• Heavy-Quarkonium Production in High Energy Proton-Proton Collisions at RHIC