Strangeness in Quark Matter 2016

Excess of J/ψ yield at very low pT in Au+Au collisions at sNN = 200 GeV and U+U at sNN = 193 GeV with STAR

28 Jun 2016, 16:20

20m

204 (Clark Kerr Campus)

Contributed Talk Quarkonia I

Speaker

Wangmei Zha (USTC/BNL)

Description

$J/\psi$ suppression 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, are likely to 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) has been observed by the ALICE collaboration in peripheral hadronic Pb+Pb collisions at $\sqrt{s_{NN}}$= 2.76 TeV at forward-rapidity, which can not be explained within the scenarios mentioned above. The observed excess may originate from the coherent photoproduction of $J/\psi$, which would be very challenging for the existing coherent photoproduction models. 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 on the STAR measurements of $J/\psi$ production at very low $p_T$ in hadronic 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 and nuclear modification factors at very low $p_T$ will also be presented. Physics perspectives with Zr+Zr and Ru+Ru collisions will be discussed.

Presentation materials

SQM_wangmei_ver7.pdf

Peer reviewing

Paper

Accepted on 30 Sept 2016 by Jochen Thaeder

Excess_of_Jpsi_ver6.pdf