Upsilon production in d+Au collisions at STAR

TL;DR

This paper reports on the measurement of Upsilon production in d+Au collisions at 200 GeV by the STAR experiment, showing results consistent with theoretical predictions and binary scaling.

Contribution

First measurement of Upsilon production in d+Au collisions at STAR, demonstrating consistency with NLO CEM predictions and binary scaling behavior.

Findings

Upsilon cross section measured as 35±4(stat)±5(sys) nb.

Nuclear modification factor R_dAu ≈ 1, indicating binary scaling.

Results align with theoretical models including anti-shadowing effects.

Abstract

We present the analysis of $\Upsilon\to e^{+}e^{-}$ production in d+Au collisions at $\sqrt{s_{NN}} = 200$ GeV from the STAR experiment. Using higher level dedicated $\Upsilon$ triggers, STAR has sampled 32 nb$^{-1}$ of integrated luminosity in year 2008 d+Au run. The cross section is found as $BR\times{({{d\sigma}\over{dy}})}_{y=0}^{\Upsilon(1S+2S+3S)}=35\pm4(stat.)\pm5(sys.)$ nb and it is consistent with NLO CEM prediction with anti-shadowing effects. In addition we calculated the nuclear modification factor $R_{dAu}=0.98\pm0.32(stat.)\pm0.28(sys.)$, which suggests the $\Upsilon(1S+2S+3S)$ production follows $N_{bin}$ scaling.