$\ensuremath{\Upsilon}(1S+2S+3S)$ production in $d$+Au and $p+p$ collisions at $\sqrt{{s}_{{}_{NN}}}=200$ GeV and cold-nuclear-matter effects

$Υ (1 S + 2 S + 3 S)$ production in $d$ +Au and $p + p$ collisions at $\sqrt{s_{_{N N}}} = 200$ GeV and cold-nuclear-matter effects

A. Adare et al. (PHENIX Collaboration)

Phys. Rev. C 87, 044909 – Published 25 April 2013

Abstract

The three $Υ$ states, $Υ (1 S + 2 S + 3 S)$ , are measured in $d + Au$ and $p + p$ collisions at $\sqrt{s_{_{N N}}} = 200$ GeV and rapidities $1.2 < | y | < 2.2$ by the PHENIX experiment at the Relativistic Heavy Ion Collider. Cross sections for the inclusive $Υ (1 S + 2 S + 3 S)$ production are obtained. The inclusive yields per binary collision for $d + Au$ collisions relative to those in $p + p$ collisions ( $R_{d Au}$ ) are found to be $0.62 \pm 0.26 (stat) \pm 0.13 (syst)$ in the gold-going direction and $0.91 \pm 0.33 (stat) \pm 0.16 (syst)$ in the deuteron-going direction. The measured results are compared to a nuclear-shadowing model, EPS09 [Eskola et al., J. High Energy Phys. 04 (2009) 065], combined with a final-state breakup cross section, $σ_{br}$ , and compared to lower energy $p + A$ results. We also compare the results to the PHENIX $J / ψ$ results [Adare et al., Phys. Rev. Lett. 107, 142301 (2011)]. The rapidity dependence of the observed $Υ$ suppression is consistent with lower energy $p + A$ measurements.