Measurements of Prompt Photon Photoproduction at HERA

Lee, Sung Won (2000) Measurements of Prompt Photon Photoproduction at HERA. PhD thesis, University of Glasgow.

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Abstract

Measurements of inclusive prompt photon and prompt photons, together with an accompanying jet, in photoproduction at HERA have been made with the ZEUS detector, using an integrated luminosity of 38.4 pb-1. We have performed two analyses in the study of prompt photon production. First inclusive cross section measurements for prompt photon production have been presented as a function of the pseudorapidity and the transverse energy (etagamma, ETgamma)of the photon, for ETgamma > 5 GeV in the gammap centre-of-mass energy range 134-285 GeV. Comparisons are made with predictions from Monte Carlo models having leading-logarithm parton showers, and with next-to-leading order QCD calculations, using currently available parameterisations of the photon structure. For positive etagamma (proton direction) there is good agreement, but for negative etagamma all predictions fall below the data. None of the available variations of the model parameters was found to be capable of removing the discrepancy with the data. The results indicated a need to review the present theoretical modelling of the parton structure of the photon at high xgamma regions. A study of the intrinsic parton transverse momentum, kT, of the quarks in the proton, as modelled within the framework of the PYTHIA Monte Carlo, has been performed using the kinematical properties of events with a measured jet as well as a prompt photon. A fit to the data gives a value of = 1.39 +/- 0.36+0.12-0.23GeV. This result is compared with earlier high-energy proton-scattering measurements. A rising trend of with interaction energy is confirmed.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: Peter Bussey
Keywords: High energy physics
Date of Award: 2000
Depositing User: Enlighten Team
Unique ID: glathesis:2000-75824
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 19 Dec 2019 09:15
Last Modified: 19 Dec 2019 09:15
URI: http://theses.gla.ac.uk/id/eprint/75824

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