# 10th International Conference on Hard and Electromagnetic Probes of High-Energy Nuclear Collisions

May 31, 2020 to June 5, 2020
Online
US/Central timezone

## Probing QCD medium effects in pPb collisions via the multiplicity dependence of J/$\psi$ and $\psi$(2S) production with the CMS experiment

Jun 1, 2020, 11:20 AM
20m
https://cern.zoom.us/j/91040899953

#### https://cern.zoom.us/j/91040899953

Oral Presentation Heavy Flavor and Quarkonia

### Speaker

Yousen Zhang (Rice University (US))

### Description

Evidence for collectivity and effects beyond nPDF modifications and energy loss in small systems has been observed in recent years. In high-multiplicity pPb events, J/$\psi$ is found to show a surprisingly large long-range elliptic anisotropy signal, comparable to that for light and open-heavy flavor hadrons. In addition, results on prompt J/$\psi$ and $\psi(2S)$ production in pPb data at 5.02 TeV exhibit a different modification of the ground and excited state, especially in the Pb-going direction, hinting to a possible breakup of the weaker bound excited states from interactions with final state particles. To better understand the production mechanism of charmonia in small systems as well as the importance of final-state effects, the multiplicity dependence of J/$\psi$ and $\psi(2S)$ production yields and forward-backward asymmetries in pPb collisions at 8.16 TeV using full LHC run 2 statistics have been studied, and the results will be presented in this talk.

Track Heavy Flavor and Quarkonia Contributed Talk CMS

### Primary author

Serguei Petrushanko (M.V. Lomonosov Moscow State University (RU))

### Presentation materials

 HardProbe2020_yousen_v5.pdf Recording