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Title: Ultra-peripheral heavy-ion collisions with CMS

Ultra-peripheral collisions (UPCs) of heavy ions involve long range electromagnetic interactions at impact parameters larger than twice the nuclear radius. At TeV energies, the strong electromagnetic field due to the coherent action of the Z = 82 proton charges generates a large flux of photons, which can be used for high-energy photoproduction studies. Heavy vector mesons produced in electromagnetic interactions provide direct information on the parton distribution functions in the nucleus at very low values of Bjorken-x. These events are characterized by a very low hadron multiplicity. The wide pseudo-rapidity coverage of the CMS detectors is used to separate such events from very peripheral nuclear interactions. The CMS experiment has excellent capabilities for the measurement of the heavy vector mesons in the dimuon decay channel using the tracker and the muon chambers. This analysis demonstrates CMS’s capabilities for measuring J/ψ and the two-photon process in ultra-peripheral collisions, using the 2011 PbPb and 2013 pPb data. The prospects for future measurements using the data to be collected in the 2015 PbPb run will be described.
Authors:
 [1]
  1. The University of Kansas, Lawrence, KS (United States)
Publication Date:
OSTI Identifier:
22391387
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1654; Journal Issue: 1; Conference: DIFFRACTION 2014: International Workshop on Diffraction in High-Energy Physics, Primosten (Croatia), 10-16 Sep 2014; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; COLLIDING BEAMS; DIFFRACTION MODELS; DISTRIBUTION FUNCTIONS; ELECTROMAGNETIC FIELDS; IMPACT PARAMETER; J PSI-3097 MESONS; LEAD 208 BEAMS; LEAD 208 REACTIONS; MULTIPARTICLE SPECTROMETERS; MULTI-PHOTON PROCESSES; MULTIPLICITY; MUONS; PARTICLE IDENTIFICATION; PARTICLE RAPIDITY; PERIPHERAL COLLISIONS; PHOTONS; PHOTOPRODUCTION; PROTONS; TEV RANGE