Nuclear Modifications of Parton Distribution Functions

Bibliographic Details
Main Author:	Adeluyi, Adeola Adeleke
Language:	English
Published:	Kent State University / OhioLINK 2009
Subjects:	Nuclear Physics parton distributions nuclear modifications
Online Access:	http://rave.ohiolink.edu/etdc/view?acc_num=kent1242182608

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spelling	ndltd-OhioLink-oai-etd.ohiolink.edu-kent12421826082021-08-03T05:36:49Z Nuclear Modifications of Parton Distribution Functions Adeluyi, Adeola Adeleke Nuclear Physics parton distributions nuclear modifications <p>This dissertation addresses a central question of modern nuclear physics: howdoes the behavior of fundamental degrees of freedom (quarks and gluons) changein the nuclear environment? This is an important aspect of experimentalstudies at current facilities such as the Relativistic Heavy Ion Collider(RHIC) at Brookhaven National Laboratory and the Continuous Electron Beam Accelerator Facility (CEBAF) at the Thomas JeffersonNational Laboratory (JLAB). It is also highly relevant to plannedexperimental efforts at the Large Hadron Collider (LHC) and the future Electron Ion Collider (EIC). All these facilities probe matter via collisions involving nuclei; thus complications arise due to the presence of the attendant nuclear medium. Theoretical efforts to understand andinterpret experimental results from such collisions are therefore largelydependent on the resolution of this question. </p><p>The development of nuclear physics demonstrates that theoretical descriptionis most efficient in terms of the effective degrees of freedom relevant tothe scale (energy) being probed. Thus at low energies, nuclei are described as bound states of protons and neutrons (nucleons). At higher energies, thenucleons are no longer elementary, but are revealed to possess an underlying substructure: they are made up of quarks and gluons, collectively termedpartons. The momentum distributions of these partons in the nucleon arereferred to as Parton Distribution Functions (PDFs).</p><p>Parton distributions can be determined from experimental measurements ofstructure functions. The ratio of nuclear structure functions to nucleonstructure functions (generically referred to as nuclear ratio) is a measure of the nuclear modifications of the free nucleon PDFs. Thus a study of the nuclearratio suffices to gain an understanding of nuclear modifications.</p><p>In this dissertation we aim to describe theoretically nuclear modifications in arestricted region where the nuclear ratio is less than unity, the so-called shadowing region. We also investigate the effects of nuclear modifications on observed quantities in ultrarelativistic nucleus-nucleus collisions. Specifically, we consider deuteron-gold collisions and observables which are directly impacted by modifications, such as pseudorapidity asymmetry andnuclear modification factors. </p><p>A good description of the shadowing region is afforded by Gribov Theory. Gribov related the shadowing correction to the differential diffractive hadron-nucleon cross section. We generalize Gribov theory to include both the real part of the diffractive scattering amplitude and higher order multiple scattering necessary for heavy nuclei. Thediffractive dissociation inputs are taken from experiments. We calculate observables in deuteron-gold collisions.Utilizing the factorization theorem, we use the existing parameterizations of nuclear PDFs and fragmentation functions in a pQCD-improved parton model to calculate nuclear modification factors and pseudorapidity asymmetries. The nuclear modification factor is essentially the ratio of the deuteron-gold cross section to that of the proton-proton cross section scaled by the number of binary collisions. The pseudorapidity asymmetry is the ratio of the cross section in the negative rapidity region relative to that in the equivalent positive rapidity region. Both quantities are sensitive to the effects of nuclear modifications on PDFs.Results are compared to experimental data from the BRAHMS and STAR collaborations.</p> 2009-06-17 English text Kent State University / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=kent1242182608 http://rave.ohiolink.edu/etdc/view?acc_num=kent1242182608 unrestricted This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.
collection	NDLTD
language	English
sources	NDLTD
topic	Nuclear Physics parton distributions nuclear modifications
spellingShingle	Nuclear Physics parton distributions nuclear modifications Adeluyi, Adeola Adeleke Nuclear Modifications of Parton Distribution Functions
author	Adeluyi, Adeola Adeleke
author_facet	Adeluyi, Adeola Adeleke
author_sort	Adeluyi, Adeola Adeleke
title	Nuclear Modifications of Parton Distribution Functions
title_short	Nuclear Modifications of Parton Distribution Functions
title_full	Nuclear Modifications of Parton Distribution Functions
title_fullStr	Nuclear Modifications of Parton Distribution Functions
title_full_unstemmed	Nuclear Modifications of Parton Distribution Functions
title_sort	nuclear modifications of parton distribution functions
publisher	Kent State University / OhioLINK
publishDate	2009
url	http://rave.ohiolink.edu/etdc/view?acc_num=kent1242182608
work_keys_str_mv	AT adeluyiadeolaadeleke nuclearmodificationsofpartondistributionfunctions
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Nuclear Modifications of Parton Distribution Functions

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