Diffraction in highenergy collisions
(2019) Abstract (Swedish)
 Denne afhandling omhandler processer med lave impulsoverførsler i højenergi partikel kollisioner. Disse processer kan ikke beskrives med perturbativ QCD, og baseres derfor ofte på Regge teori, udviklet før QCD. Flere modeller er udviklet indenfor dette område, og enkelte er i denne afhandling blevet udviklet og studeret. Alle modeller er implementeret som numeriske simuleringer (en Monte Carlo event generator), som giver mulighed for præcise forudsigelser for forskellige typer partikelkollisioner.
 Abstract
 This thesis concerns itself with lowmomentumtransfer processes in highenergy particle collisions. These processes cannot be described in the framework of the fundamental theory of quantum chromodynamics (QCD), but rely on a preQCD approach, the Regge theory. Several models containing various degrees of complexity have been proposed within this framework, some of which have been developed and studied in this thesis. All models have been implemented in a numerical simulation (a Monte Carlo event generator), which allows for
precise predictions of several types of particle collisions at various energies.
Paper I: A model for hard diffractive events in pp collisions is proposed. It is based on evaluating a probability for... (More)  This thesis concerns itself with lowmomentumtransfer processes in highenergy particle collisions. These processes cannot be described in the framework of the fundamental theory of quantum chromodynamics (QCD), but rely on a preQCD approach, the Regge theory. Several models containing various degrees of complexity have been proposed within this framework, some of which have been developed and studied in this thesis. All models have been implemented in a numerical simulation (a Monte Carlo event generator), which allows for
precise predictions of several types of particle collisions at various energies.
Paper I: A model for hard diffractive events in pp collisions is proposed. It is based on evaluating a probability for diffraction, but employs an additional dynamical choice of survival of the proposed diffractive events. This dynamical description is the first of its kind and offers an explanation of earlier discrepancies between data and theory.
Paper II: Existing models are reviewed and new ones developed for all components of the pp cross section; the total, elastic and diffractive cross sections. The models are implemented in the event generator Pythia 8, thus offering improved predictions for these collisions at LHC energies.
Paper III: In this work the model for hard diffraction is extended to photoproduction. The dynamical survival effect is by construction only present in a subset of these collisions and thus puts forward an explanation of the discrepancies between data and theory of hard diffractive dijet events in the photoproduction regime.
Paper IV: Here a new model for intial state evolution is implemented and studied in Pythia 8. This model opens up for asymmetrical matter distributions within the colliding particles, and consequences because of these asymmetries are studied within ep, pp, pA and AA collisions. Predictions for the color fluctuations in the cross
sections in eA collisions are presented as a first step towards a complete description of electronion collisions.
(Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/record/a71ba614a8574f4295757ca845761c0d
 author
 Rasmussen, Christine ^{LU}
 supervisor

 Torbjörn Sjöstrand ^{LU}
 Leif Lönnblad ^{LU}
 opponent

 Professor Motyka, Laszek, Jagiellonian University, Krakow, Poland
 organization
 alternative title
 Diffraktion i højenergi fysik
 publishing date
 2019
 type
 Thesis
 publication status
 published
 subject
 keywords
 QCD, Soft QCD, phenomenology, Diffraction, Multiparton Interactions, Dipole model, Initial state evolution, BFKL evolution.
 pages
 263 pages
 publisher
 Lund
 defense location
 Lundmarksalen, Astronomihuset, Sölvegatan 27, Lund
 defense date
 20190927 10:00
 ISBN
 9789178952151
 9789178952168
 language
 English
 LU publication?
 yes
 id
 a71ba614a8574f4295757ca845761c0d
 date added to LUP
 20190830 09:19:05
 date last changed
 20191004 12:10:15
@phdthesis{a71ba614a8574f4295757ca845761c0d, abstract = {This thesis concerns itself with lowmomentumtransfer processes in highenergy particle collisions. These processes cannot be described in the framework of the fundamental theory of quantum chromodynamics (QCD), but rely on a preQCD approach, the Regge theory. Several models containing various degrees of complexity have been proposed within this framework, some of which have been developed and studied in this thesis. All models have been implemented in a numerical simulation (a Monte Carlo event generator), which allows for<br/>precise predictions of several types of particle collisions at various energies.<br/>Paper I: A model for hard diffractive events in pp collisions is proposed. It is based on evaluating a probability for diffraction, but employs an additional dynamical choice of survival of the proposed diffractive events. This dynamical description is the first of its kind and offers an explanation of earlier discrepancies between data and theory.<br/>Paper II: Existing models are reviewed and new ones developed for all components of the pp cross section; the total, elastic and diffractive cross sections. The models are implemented in the event generator Pythia 8, thus offering improved predictions for these collisions at LHC energies.<br/>Paper III: In this work the model for hard diffraction is extended to photoproduction. The dynamical survival effect is by construction only present in a subset of these collisions and thus puts forward an explanation of the discrepancies between data and theory of hard diffractive dijet events in the photoproduction regime.<br/>Paper IV: Here a new model for intial state evolution is implemented and studied in Pythia 8. This model opens up for asymmetrical matter distributions within the colliding particles, and consequences because of these asymmetries are studied within ep, pp, pA and AA collisions. Predictions for the color fluctuations in the cross<br/>sections in eA collisions are presented as a first step towards a complete description of electronion collisions.<br/>}, author = {Rasmussen, Christine}, isbn = {9789178952151}, keyword = {QCD,Soft QCD,phenomenology,Diffraction,Multiparton Interactions,Dipole model,Initial state evolution,BFKL evolution.}, language = {eng}, pages = {263}, publisher = {Lund}, school = {Lund University}, title = {Diffraction in highenergy collisions}, year = {2019}, }