Structure of the Virtual Photon at HERA

Macdonald, Neil Scott (1999) Structure of the Virtual Photon at HERA. PhD thesis, University of Glasgow.

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The dependence of the structure of the photon on its virtuality, Q2, and on the scale of the probing jets, is investigated by measuring the reaction e+p → e+ + jet + jet + X with the ZEUS detector at HERA. Samples of such events ranging from Q2 ≈ 0 GeV2 to Q2 of 5000 GeV2 have been selected from the data taken in 1996 and 1997, corresponding to an integrated luminosity of 38.1 pb-1. The measured inclusive differential dijet cross section dsigma/dxobsgamma is presented as a function of Q2 and the square of the transverse energy of the jets, E2T, where xgammaobs is an estimator of the fraction of the photon's momentum participating in the hard dijet subprocess, and compared with the predictions of leading order Monte Carlo programs for various photon parton distribution functions. The ratio of dijet cross sections with xgammaobs 0.75 show the number of events exhibiting resolved photonic structure to decrease relative to those events without such structure as the photon virtuality increases, whilst the dependence on the scale of the probing jets is small. In comparing simulated Monte Carlo events with the data, it is found that events which simulate photonic structure are needed up to a virtuality of at least 10.5 GeV2.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: Costas Foundas
Keywords: High energy physics
Date of Award: 1999
Depositing User: Enlighten Team
Unique ID: glathesis:1999-76353
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 19 Nov 2019 15:22
Last Modified: 19 Nov 2019 15:22

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