Upsilon Measurements by the PHENIX Collaboration

TL;DR

This paper reports on measurements of Upsilon particle production in different collision systems at 200 GeV, revealing no suppression in p+p, cold nuclear matter effects in d+Au, and possible suppression in Au+Au collisions.

Contribution

First baseline cross-section measurement in p+p collisions and initial insights into Upsilon suppression across collision types at RHIC.

Findings

No suppression in p+p collisions.

Cold nuclear matter effects observed in d+Au.

Hints of suppression in Au+Au collisions.

Abstract

PHENIX has measured $\Upsilon$ production in p+p, d+Au and Au+Au collisions at $\sqrt{s_{NN}}$=200 GeV. A baseline cross-section measurement has been made in p+p collisions. Preliminary studies of d+Au collisions found no suppression in the backward direction, but suppression was observed in the forward direction indicating the presence of cold nuclear matter effects. In Au+Au collisions preliminary studies of $\Upsilon$ production at mid-rapidity found hints of suppression.