Loading...
Coherent J/ψ photoproduction in ultra-peripheral PbPb collisions at √sNN= 2.76 TeV with the CMS experiment
CMS Collaboration
CMS Collaboration
Citations
Altmetric:
Abstract
The cross section for coherent J/ψ photoproduction accompanied by at least one neutron on one side of the interaction point and no neutron activity on the other side, Xn0n, is measured with the CMS experiment in ultra-peripheral PbPb collisions at √sNN= 2.76TeV. The analysis is based on a data sample corresponding to an integrated luminosity of 159 μb−1, collected during the 2011 PbPb run. The J/ψ mesons are reconstructed in the dimuon decay channel, while neutrons are detected using zero degree calorimeters. The measured cross section is dσcohXn0n/dy(J/ψ ) = 0.36 ± 0.04 (stat) ±0.04 (syst) mb in the rapidity interval 1.8 < |y| < 2.3. Using a model for the relative rate of coherent photoproduction processes, this Xn0nmeasurement gives a total coherent photoproduction cross section of dσcoh/dy(J/ψ ) = 1.82±0.22 (stat)±0.20 (syst)±0.19 (theo) mb. The data strongly disfavor the impulse approximation model prediction, indicating that nuclear effects are needed to describe coherent J/ψphotoproduction in γ + Pb interactions. The data are found to be consistent with the leading twist approximation, which includes nuclear gluon shadowing.
Description
Date
2018-09
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier
Collections
Files
Research Projects
Organizational Units
Journal Issue
Keywords
CMS, Physics, Heavy ion collisions, Ultra-peripheral collisions, UPC, J/Psi
Citation
The CMS collaboration, Coherent J/ψ photoproduction in ultra-peripheral PbPb collisions at √sNN= 2.76 TeV with the CMS experiment, Physics Letters B. (2017) 772: 489-511. https://doi.org/10.1016/j.physletb.2017.07.001