# Quark Matter 2017

5-11 February 2017
Hyatt Regency Chicago
America/Chicago timezone

## $J/\psi$ production in p+p collisions at $\sqrt{s}$ = 500 GeV at the STAR experiment

Not scheduled
2h 30m
Hyatt Regency Chicago

#### Hyatt Regency Chicago

151 East Wacker Drive Chicago, Illinois, USA, 60601
Board: D17
Poster

### Speaker

Qian Yang (University of Science and Technology of China)

### Description

Understanding $J/\psi$ meson hadroproduction has been a long-term effort both experimentally and theoretically. However, none of the existing theoretical models can successfully describe both $J/\psi$ transverse momentum ($p_{T}$) spectrum and the polarization. Furthermore, the composition of inclusive $J/\psi$ is complicated, including direct production via gluon fusion, parton fragmentation, and feed-down from excited charmonium states and B hadrons. Measurements of $J/\psi$ production at a different beam energy can shed new lights on the understanding of different $J/\psi$ production mechanisms, and help to constrain model calculations.

We report measurements of $J/\psi$ production in p+p collisions at $\sqrt{s}$ = 500 GeV in both the di-electron and di-muon channels. By combining measurements from these two channels, the $p_{T}$ spectrum of $J/\psi$ is measured from 0 to 20 GeV/$c$ and compared with NLO NRQCD and CGC+NRQCD calculations at different kinematic ranges. Feed-down contributions from $\psi(2S)$ is studied in the $p_{T}$ range of $4 < p_{T} < 12$ GeV/$c$. In addition, measurements of the $J/\psi$ production as a function of charged-particle multiplicity will be presented. A strong increase of the relative $J/\psi$ yield with multiplicity is observed for all $p_{T}$ bins with significant $p_{T}$ dependence. The results are compared with predications from the Percolation model and PYTHIA8

Preferred Track Quarkonia STAR

### Primary author

Qian Yang (University of Science and Technology of China)

### Presentation materials

There are no materials yet.