Aspects of QCD and the Photon Structure
(2000) Abstract
 In a single theoretical framework, real and virtual photon interactions are modeled for gammap and gammagamma collisions. The description covers aspects from the production of jets to total cross sections, where special emphasis is put on the range of uncertainty in the modeling of a resolved photon component. Our approach extends on a model for photoproduction, where the total cross section is subdivided into three distinct event classes: direct, VMD and anomalous. It provides a smooth transition between the region of real and highly virtual photons. In jet production, photon flux factors are convoluted with matrix elements involving either direct or resolved photons and, for the latter, with parton distributions of the photon. Effects... (More)
 In a single theoretical framework, real and virtual photon interactions are modeled for gammap and gammagamma collisions. The description covers aspects from the production of jets to total cross sections, where special emphasis is put on the range of uncertainty in the modeling of a resolved photon component. Our approach extends on a model for photoproduction, where the total cross section is subdivided into three distinct event classes: direct, VMD and anomalous. It provides a smooth transition between the region of real and highly virtual photons. In jet production, photon flux factors are convoluted with matrix elements involving either direct or resolved photons and, for the latter, with parton distributions of the photon. Effects of resolved longitudinal photons are estimated by simple multiplicative factors on the resolved transversephoton contributions and their impact on some representative distributions are investigated. Complete events are generated with Monte Carlo methods and results are confronted with data from specifically HERA and LEP2. By the breakdown into different event classes, we aim for a complete picture of all event properties in gammap and gammagamma collisions.
When there are identical colour charges in a parton cascade, there are several ways to stretch a string, or a cluster chain, in the subsequent hadronization phase. In particular, the possibility that a colour singlet gluon system hadronizes isolated from the remainder of the system in hadronic Z decays is studied.
QCD aspects of leptoquark production at HERA are discussed with focus on initial and finalstate QCD radiation. By taking into account corrections to this, in mass reconstructions of a leptoquark, a narrower mass peak and a better average mass value is obtained. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/record/40776
 author
 Friberg, Christer ^{LU}
 opponent

 Dr Forshaw, Jeffrey R., Department of Physics and AstronomyThe University of ManchesterThe U.K.
 organization
 publishing date
 2000
 type
 Thesis
 publication status
 published
 subject
 keywords
 High energy interactions, QCD, Photons, Monte Carlo Event Generator, Leptoquarks, Colour Connections, cosmic rays, Kosmisk strålning, högenergi, Fysicumarkivet A:2000:Friberg
 pages
 212 pages
 publisher
 Department of Theoretical Physics, Lund University
 defense location
 Lecture Hall F, Dept. of Theoretical Physics
 defense date
 20001006 10:15
 ISBN
 9178740584
 language
 English
 LU publication?
 yes
 id
 2a7dca56425049538a51a65cba7e8b9a (old id 40776)
 date added to LUP
 20070731 08:49:25
 date last changed
 20180529 12:26:20
@phdthesis{2a7dca56425049538a51a65cba7e8b9a, abstract = {In a single theoretical framework, real and virtual photon interactions are modeled for gammap and gammagamma collisions. The description covers aspects from the production of jets to total cross sections, where special emphasis is put on the range of uncertainty in the modeling of a resolved photon component. Our approach extends on a model for photoproduction, where the total cross section is subdivided into three distinct event classes: direct, VMD and anomalous. It provides a smooth transition between the region of real and highly virtual photons. In jet production, photon flux factors are convoluted with matrix elements involving either direct or resolved photons and, for the latter, with parton distributions of the photon. Effects of resolved longitudinal photons are estimated by simple multiplicative factors on the resolved transversephoton contributions and their impact on some representative distributions are investigated. Complete events are generated with Monte Carlo methods and results are confronted with data from specifically HERA and LEP2. By the breakdown into different event classes, we aim for a complete picture of all event properties in gammap and gammagamma collisions.<br/><br> <br/><br> When there are identical colour charges in a parton cascade, there are several ways to stretch a string, or a cluster chain, in the subsequent hadronization phase. In particular, the possibility that a colour singlet gluon system hadronizes isolated from the remainder of the system in hadronic Z decays is studied.<br/><br> <br/><br> QCD aspects of leptoquark production at HERA are discussed with focus on initial and finalstate QCD radiation. By taking into account corrections to this, in mass reconstructions of a leptoquark, a narrower mass peak and a better average mass value is obtained.}, author = {Friberg, Christer}, isbn = {9178740584}, keyword = {High energy interactions,QCD,Photons,Monte Carlo Event Generator,Leptoquarks,Colour Connections,cosmic rays,Kosmisk strålning,högenergi,Fysicumarkivet A:2000:Friberg}, language = {eng}, pages = {212}, publisher = {Department of Theoretical Physics, Lund University}, school = {Lund University}, title = {Aspects of QCD and the Photon Structure}, year = {2000}, }