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Gunther M. Roland. Baty, Austin A. Massachusetts Institute of Technology. Department of Physics. Massachusetts Institute of Technology. Department of Physics 2020-01-08T19:32:46Z 2020-01-08T19:32:46Z 2019 2019 https://hdl.handle.net/1721.1/123355 1132808066 This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. Thesis: Ph. D., Massachusetts Institute of Technology, Department of Physics, 2019 Cataloged from student-submitted PDF version of thesis. Includes bibliographical references (pages 223-245). The phenomenology of the strong nuclear force is still not well understood at low momentum transfers and requires experimental input to constrain. Collisions of heavy ions at the Large Hadron Collider provide a unique opportunity to explore this kinematic region because they create a novel form of matter: the quark-gluon plasma (QGP). Using the CMS detector, spectra of charged particles originating from protonproton (pp), proton-lead (pPb), and lead-lead (PbPb) collisions at a center of mass energy per nucleon pair ( [square root of SNN) of 5.02 TeV are examined as a function of transverse momentum and centrality. Nuclear modification factors and fragmentation functions are constructed from these spectra. By comparing to pp collision reference spectra, a puzzle concerning previous measurements in pPb collisions is clarified. A strong suppression of particle production observed in PbPb collisions is also quantified. Finally, collisions of xenon nuclei are also studied to constrain the path length dependence of parton energy loss. The strength of energy loss is found to increase with both [square root of SNN and the average path length through the QGP. Comparisons to theoretical models and previous measurements indicate that the path length dependence is between linear and quadratic, as expected from a combination of collisional and radiative energy loss mechanisms. by Austin A. Baty. Ph.D. Ph.D. Massachusetts Institute of Technology, Department of Physics 245 pages eng Massachusetts Institute of Technology MIT theses are protected by copyright. They may be viewed, downloaded, or printed from this source but further reproduction or distribution in any format is prohibited without written permission. http://dspace.mit.edu/handle/1721.1/7582 Physics. Study of parton energy loss in heavy ion collisions using charged particle spectra measured with CMS Thesis application/pdf 2020-01-08T19:32:46Z Publication Doctoral Phys unknown unknown <Publication xmlns="https://www.openaire.eu/cerif-profile/1.1/" id="d1eb75b0-20f4-4771-b74d-569e727e3427"> <Type xmlns="https://www.openaire.eu/cerif-profile/vocab/COAR_Publication_Types">http://purl.org/coar/resource_type/c_1843</Type> <Language>eng</Language> <Title>Study of parton energy loss in heavy ion collisions using charged particle spectra measured with CMS</Title> <PublishedIn> <Publication> </Publication> </PublishedIn> <PublicationDate>2019</PublicationDate> <Authors> <Author> <DisplayName>Baty, Austin A.</DisplayName> <Affiliation> <OrgUnit> </OrgUnit> </Affiliation> </Author> </Authors> <Editors> </Editors> <Publishers> <Publisher> <DisplayName>Massachusetts Institute of Technology</DisplayName> <OrgUnit /> </Publisher> </Publishers> <License>http://dspace.mit.edu/handle/1721.1/7582</License> <Keyword>Physics.</Keyword> <Abstract>The phenomenology of the strong nuclear force is still not well understood at low momentum transfers and requires experimental input to constrain. Collisions of heavy ions at the Large Hadron Collider provide a unique opportunity to explore this kinematic region because they create a novel form of matter: the quark-gluon plasma (QGP). Using the CMS detector, spectra of charged particles originating from protonproton (pp), proton-lead (pPb), and lead-lead (PbPb) collisions at a center of mass energy per nucleon pair ( [square root of SNN) of 5.02 TeV are examined as a function of transverse momentum and centrality. Nuclear modification factors and fragmentation functions are constructed from these spectra. By comparing to pp collision reference spectra, a puzzle concerning previous measurements in pPb collisions is clarified. A strong suppression of particle production observed in PbPb collisions is also quantified. Finally, collisions of xenon nuclei are also studied to constrain the path length dependence of parton energy loss. The strength of energy loss is found to increase with both [square root of SNN and the average path length through the QGP. Comparisons to theoretical models and previous measurements indicate that the path length dependence is between linear and quadratic, as expected from a combination of collisional and radiative energy loss mechanisms.</Abstract> <Access xmlns="http://purl.org/coar/access_right" > </Access> </Publication>