Header

UZH-Logo

Maintenance Infos

Coherent J/ψ photoproduction in ultra-peripheral PbPb collisions at $\sqrt{s_{NN}} = 2.76$ TeV with the CMS experiment


Abstract

The cross section for coherent J/psi photoproduction accompanied by at least one neutron on one side of the interaction point and no neutron activity on the other side, $X_n 0_n$, is measured with the CMS experiment in ultra-peripheral PbPb collisions at $\sqrt{s_{NN}} = 2.76 TeV$. The analysis is based on a data sample corresponding to an integrated luminosity of 159 inverse microbarns, collected during the 2011 PbPb run. The $J/ \psi$ mesons are reconstructed in the dimuon decay channel, while neutrons are detected using zero degree calorimeters. The measured cross section is $d \sigma {^{coh}_{X_n 0_n}} / dy(J/ \psi) = 0.36 ± 0.04 (stat) ± 0.04 (syst) mb$ in the rapidity interval $1.8 < |y| < 2.3$. Using a model for the relative rate of coherent photoproduction processes, this X[z,n,z] measurement gives a total coherent photoproduction cross section of $d \sigma^{coh} / dy(J/ \psi) = 1.82 ± 0.22 (stat) ± 0.20 (syst) ± 0.19 (theo) mb$. The data strongly disfavour the impulse approximation model prediction, indicating that nuclear effects are needed to describe coherent $J/ \psi$ photoproduction in $\gamma + Pb$ interactions. The data are found to be consistent with the leading twist approximation, which includes nuclear gluon shadowing.

Abstract

The cross section for coherent J/psi photoproduction accompanied by at least one neutron on one side of the interaction point and no neutron activity on the other side, $X_n 0_n$, is measured with the CMS experiment in ultra-peripheral PbPb collisions at $\sqrt{s_{NN}} = 2.76 TeV$. The analysis is based on a data sample corresponding to an integrated luminosity of 159 inverse microbarns, collected during the 2011 PbPb run. The $J/ \psi$ mesons are reconstructed in the dimuon decay channel, while neutrons are detected using zero degree calorimeters. The measured cross section is $d \sigma {^{coh}_{X_n 0_n}} / dy(J/ \psi) = 0.36 ± 0.04 (stat) ± 0.04 (syst) mb$ in the rapidity interval $1.8 < |y| < 2.3$. Using a model for the relative rate of coherent photoproduction processes, this X[z,n,z] measurement gives a total coherent photoproduction cross section of $d \sigma^{coh} / dy(J/ \psi) = 1.82 ± 0.22 (stat) ± 0.20 (syst) ± 0.19 (theo) mb$. The data strongly disfavour the impulse approximation model prediction, indicating that nuclear effects are needed to describe coherent $J/ \psi$ photoproduction in $\gamma + Pb$ interactions. The data are found to be consistent with the leading twist approximation, which includes nuclear gluon shadowing.

Statistics

Citations

Dimensions.ai Metrics
8 citations in Web of Science®
7 citations in Scopus®
Google Scholar™

Altmetrics

Downloads

13 downloads since deposited on 08 Dec 2017
13 downloads since 12 months
Detailed statistics

Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Physics Institute
Dewey Decimal Classification:530 Physics
Language:English
Date:2017
Deposited On:08 Dec 2017 08:32
Last Modified:19 Feb 2018 08:53
Publisher:Elsevier
ISSN:0370-2693
OA Status:Gold
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1016/j.physletb.2017.07.001

Download

Download PDF  'Coherent J/ψ photoproduction in ultra-peripheral PbPb collisions at $\sqrt{s_{NN}} = 2.76$ TeV with the CMS experiment'.
Preview
Content: Published Version
Filetype: PDF
Size: 826kB
View at publisher
Licence: Creative Commons: Attribution 4.0 International (CC BY 4.0)