Coherent J/ψ photoproduction in ultra-peripheral PbPb collisions at √sNN= 2.76 TeV with the CMS experiment
Issue Date
2018-09Author
CMS Collaboration
Publisher
Elsevier
Type
Article
Article Version
Scholarly/refereed, publisher version
Rights
© 2017 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license
Metadata
Show full item recordAbstract
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.
Collections
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
Items in KU ScholarWorks are protected by copyright, with all rights reserved, unless otherwise indicated.
We want to hear from you! Please share your stories about how Open Access to this item benefits YOU.