2016/05/31 by CMS Collaboration, V. Khachatryan, A. M. Sirunyan +98 · 142 citations
Physics and Astronomy · #Astrophysics #High-Energy Particle Collisions Research #Particle physics theoretical and experimental studies #Philosophy #Physics #Quantum Chromodynamics and Particle Interactions #Scroll #Swift #Theology #hep-ex #nucl-ex
paper · pdf · doi:10.1016/j.physletb.2017.07.001
published in Physics Letters B 772, 489-511 (Elsevier BV) · Replaced with the published version. Added the journal reference and DOI. All the figures and tables can be found at http://cms-results.web.cern.ch/cms-results/public-results/publications/HIN-12-009/index.html
openalex created_date 2016/06/24 · openalex publication_date 2017/07/08 · arxiv created 2017/08/14 · arxiv updated 2017/08/15 · openalex updated_date 2026/08/05
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, X n 0 n , is measured with the CMS experiment in ultra-peripheral PbPb collisions at s N N = 2.76 TeV . 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 d σ X n 0 n coh / d y ( 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 X n 0 n measurement gives a total coherent photoproduction cross section of d σ coh / d y ( 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 / ψ photoproduction in γ + Pb interactions. The data are found to be consistent with the leading twist approximation, which includes nuclear gluon shadowing.