# Hard Probe 2016

22-27 September 2016
East Lake International Conference Center
Asia/Chongqing timezone
<a href="http://hp2016.ccnu.edu.cn">http://hp2016.ccnu.edu.cn</a>

## J/$\psi$ production in proton+proton and heavy-ion collisions at STAR

24 Sep 2016, 16:00
20m
Jing-Zhou Hall (East Lake International Convention Center)

### Speaker

Yi Yang (National Cheng Kung University)

### Description

The discovery of the J/$\psi$ meson opened the door to studying the heavy quark-antiquark system. This not only provides valuable knowledge for our understanding of Quantum Chromodynamics (QCD), but also plays an important role as a standard candle for discovering new physics. Quark Gluon Plasma (QGP) is a new phase of matter which surprisingly behaves like a perfect fluid, and it can be created in high energy heavy-ion collisions. Comparing the production properties of quarkonium states in proton+proton and heavy-ion collisions plays a crucial role in exacting the QGP properties, for example the nuclear modification factor ($R_{AA}$) and elliptic flow ($v_2$) over a broad $p_T$ range.

The STAR experiment now has the capability of studying the quarkonium states via the dimuon channel with the newly installed Muon Telescope Detector. In this talk, the J/$\psi$ production cross-section, the dependence of J/$\psi$ production yield on charged-particle multiplicity in proton+proton collisions at \sqrt{s} = 200 and 500 GeV, and the measurements of $R_{AA}$ and $v_2$ of J/$\psi$ in Au+Au collisions at \sqrt{S_{NN}} = 200 GeV using dielectron and dimuon channels at the STAR experiment will be presented. The comparisons between the measurements and various model calculations will also be discussed.

Presentation type Oral

### Primary author

Yi Yang (National Cheng Kung University)