J/Ψ production in ultra-peripheral proton-lead and lead-lead collisions with CMS
Issue Date
2017-12-31Author
Al-Bataineh, Ayman Ahmad
Publisher
University of Kansas
Format
219 pages
Type
Dissertation
Degree Level
Ph.D.
Discipline
Physics & Astronomy
Rights
Copyright held by the author.
Metadata
Show full item recordAbstract
This thesis reports on photoproduction of exclusive J/ψ mesons in ultra-peripheral PbPb and pPb collisions at √sNN = 2.76 TeV, and 5.02 TeV, respectively, from the CMS experiment at the LHC. For PbPb collisions, there is a correlation between the directions of the produced J/ψ and the neutron emitted by the struck nucleus. For J/ψ mesons with pT 100 MeV/c, the ratio of the pT distributions for J/ψ is moving in the opposite direction as the neutrons emitted from the target nucleus to those for J/ψ is moving in the same direction as the neutrons, suggests significant shadowing in the lead nucleus. For pPb collisions, the distributions of the J/ψs in transverse momentum have a similar form to previous measurements at HERA. The average pT increases with the photon-proton center of mass energy W . This implies that the spatial distribution of the gluons within the proton depends upon the gluon momentum. The cross-section also increases as W increases from 57 to 439 GeV implying that the proton becomes more and more opaque to photons as the photon energy increases. Parametrizing the growth ofthecrosssectionbytheformσ(W)∝Wδ yieldsavalueofδ =0.636±0.063. This result is consistent with the world average and has a precision comparable to other experiments.
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