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>

Excess of $J/\psi$ yield at very low $p_{T}$ in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV and U+U collisions at $\sqrt{s_{NN}}$ = 193 GeV measured with STAR experiment

25 Sep 2016, 11:40
Jing-Zhou Hall (East Lake International Conference Center)

Jing-Zhou Hall

East Lake International Conference Center

Donghu Road 142, Wuchang District, Wuhan, Hubei, China


Wangmei Zha (USTC/BNL)


Suppression of $J/\psi$ production in heavy-ion collisions due to color screening of quark and antiquark potential in the deconfined medium has been proposed as a signature of the QGP formation. Other mechanisms, such as the cold nuclear matter effects and charm quark recombination, can contribute to the observed modification of $J/\psi$ production in heavy-ion collisions. Recently, a significant excess of $J/\psi$ yield at very low $p_{T}$ ($<$ 0.3 GeV/c) was observed by the ALICE collaboration in peripheral Pb+Pb collisions at $\sqrt{s_{NN}}$= 2.76 TeV at forward-rapidity, which can not be explained by the above-mentioned effects. It has been hypothesized that such $J/\psi$'s are produced from the coherent photoproduction in Pb+Pb collisions at impact parameters smaller than twice the nuclear radius, which would be very challenging for the existing models developed to describe coherent photoproduction in ultra-peripheral collisions. Measurements of $J/\psi$ production at very low $p_{T}$ in different collision energies, collision systems, and centralities can shed new light on the origin of the excess.\

In this presentation we report the STAR measurements of $J/\psi$ production at very low $p_{T}$ in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV and U+U collisions at $\sqrt{s_{NN}}$ = 193 GeV at mid-rapidity. Centrality dependence of $J/\psi$ production cross section and nuclear modification factors at very low $p_{T}$ will be presented. Physics perspectives with Zr+Zr and Ru+Ru collisions scheduled for RHIC 2018 run will be discussed.

Presentation type Oral

Primary author

Wangmei Zha (USTC/BNL)

Presentation Materials

Your browser is out of date!

If you are using Internet Explorer, please use Firefox, Chrome or Edge instead.

Otherwise, please update your browser to the latest version to use Indico without problems.