# Quark Matter 2018

May 13 – 19, 2018
Venice, Italy
Europe/Zurich timezone
The organisers warmly thank all participants for such a lively QM2018! See you in China in 2019!

## J/psi coherent photo-production at very low transverse momentum in Pb-Pb collisions at sqrt{s_{NN}} = 5.02 TeV with ALICE

May 15, 2018, 5:00 PM
2h 40m
First floor and third floor (Palazzo del Casinò)

Poster Quarkonia

### Speaker

Zhuo Zhou (University of Bergen (NO))

### Description

A large excess in the yield of $\mathrm{J/\psi}$ at very low transverse momentum (${p}_\mathrm{T}<\mathrm{300\ MeV/}c$) and forward rapidity (2.5< $y$ <4.0) was recently reported by ALICE using the LHC Run-1 data, in Pb-Pb collisions at $\sqrt{s_\mathrm{NN}}$ = 2.76 TeV. This is suggestive of coherent $\mathrm{J/\psi}$ photo-production, similar to measurements in ultra-peripheral collisions (UPC), where the nuclei only interact electromagnetically.

During the LHC Run-2, the measurement of the very low ${p}_\mathrm{T}$ $\mathrm{J/\psi}$ at mid-rapidity (-0.9< $y$ <0.9) in the di-electron decay channel was possible thanks to the large sample of recorded Pb-Pb collisions. The central barrel detectors provide a good momentum resolution, and make the measurement sensitive to the key characteristics of $\mathrm{J/\psi}$ coherent photo-production, like the corresponding transverse momentum spectrum.

In this poster, we will present the ${p}_\mathrm{T}$-integrated and ${p}_\mathrm{T}$-dependent coherent $\mathrm{J/\psi}$ photo-production cross-section at mid rapidity in Pb-Pb collisions at $\sqrt{s_\mathrm{NN}}$ = 5.02 TeV. Our data will be discussed in comparison to the UPC measurements and model calculations. The expectations for this measurements with LHC Run-3 and Run-4 data will be discussed.

Centralised submission by Collaboration Presenter name already specified ALICE Experiment

### Primary author

Zhuo Zhou (University of Bergen (NO))