{"id":{"repo_id":"penn","oai_identifier":"oai:repository.upenn.edu:20.500.14332/30484"},"canonical_url":"https://search.dev.ndltd.org/etd/penn/oai:repository.upenn.edu:20.500.14332/30484","repository":{"repo_id":"penn","name":"University of Pennsylvania","base_url":"https://repository.upenn.edu/server/oai/request"},"display":{"title":"Targeting Natural Supersymmetry With Top Quarks","abstract":"This thesis describes a search for natural supersymmetry via the production of light top squarks (stops) with the ATLAS experiment, using 13 TeV proton-proton collision data delivered by the Large Hadron Collider. A range of models is considered where the stop may decay to top quarks, b jets, and a variety of other supersymmetric particles. Stop masses as large as 950 GeV are excluded at 95% confidence level when decaying to a top quark and massless lightest supersymmetric particle (LSP). In scenarios where the LSP is a Higgsino, exclusions vary from 600 to 900 GeV depending on the relative stop branching fractions and Higgsino mass splitting. The impact of precision top-quark measurements on future searches is also discussed, including a measurement of quantum interference in top-quark production and measurement of the top-quark width. A differential mass distribution is measured in events with two charged leptons and two b-tagged jets that is sensitive to the interference property. The measurement is unfolded to particle level and the data are compared to state-of-the-art Monte Carlo predictions, which are found to describe the data well. A new technique is proposed to utilize this dataset to extract a value of the top-quark width, inspired by recent efforts to measure the Higgs boson width using off-shell decays. A value of 1.28 ± 0.27(exp.)±0.15(theory) GeV is extracted from the ATLAS data, in good agreement with the standard model prediction. Finally, a new hardware tracking system is described for use in the upgraded ATLAS Trigger system for the high-luminosity run of the LHC.","abstract_html":"This thesis describes a search for natural supersymmetry via the production of light top squarks (stops) with the ATLAS experiment, using 13 TeV proton-proton collision data delivered by the Large Hadron Collider. A range of models is considered where the stop may decay to top quarks, b jets, and a variety of other supersymmetric particles. Stop masses as large as 950 GeV are excluded at 95% confidence level when decaying to a top quark and massless lightest supersymmetric particle (LSP). In scenarios where the LSP is a Higgsino, exclusions vary from 600 to 900 GeV depending on the relative stop branching fractions and Higgsino mass splitting. The impact of precision top-quark measurements on future searches is also discussed, including a measurement of quantum interference in top-quark production and measurement of the top-quark width. A differential mass distribution is measured in events with two charged leptons and two b-tagged jets that is sensitive to the interference property. The measurement is unfolded to particle level and the data are compared to state-of-the-art Monte Carlo predictions, which are found to describe the data well. A new technique is proposed to utilize this dataset to extract a value of the top-quark width, inspired by recent efforts to measure the Higgs boson width using off-shell decays. A value of 1.28 ± 0.27(exp.)±0.15(theory) GeV is extracted from the ATLAS data, in good agreement with the standard model prediction. Finally, a new hardware tracking system is described for use in the upgraded ATLAS Trigger system for the high-luminosity run of the LHC.","abstract_has_math":false,"creators":["Herwig, Theodor Christian"],"institution":null,"degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["Elliot Lipeles"],"committee_chairs":[],"committee_members":[],"year":2019,"date_issued":"2019","date_published":"2019","updated_at":"2026-07-24T03:46:32Z","subjects":[],"languages":["en"],"rights":["Theodor Christian Herwig"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://repository.upenn.edu/handle/20.500.14332/30484","outbound_label":"Repository record","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Elliot Lipeles"]},{"key":"dc:creator","label":"Author","values":["Herwig, Theodor Christian"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2023-05-17T22:58:14.000"]},{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2023-05-22T17:42:10Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2001-01-01T00:00:00Z"]},{"key":"dc:date.issued","label":"Date","values":["2019"]},{"key":"dc:type","label":"Dc Type","values":["Dissertation/Thesis"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Theodor Christian Herwig"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://repository.upenn.edu/handle/20.500.14332/30484"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["This thesis describes a search for natural supersymmetry via the production of light top squarks (stops) with the ATLAS experiment, using 13 TeV proton-proton collision data delivered by the Large Hadron Collider. A range of models is considered where the stop may decay to top quarks, b jets, and a variety of other supersymmetric particles. Stop masses as large as 950 GeV are excluded at 95% confidence level when decaying to a top quark and massless lightest supersymmetric particle (LSP). In scenarios where the LSP is a Higgsino, exclusions vary from 600 to 900 GeV depending on the relative stop branching fractions and Higgsino mass splitting. The impact of precision top-quark measurements on future searches is also discussed, including a measurement of quantum interference in top-quark production and measurement of the top-quark width. A differential mass distribution is measured in events with two charged leptons and two b-tagged jets that is sensitive to the interference property. The measurement is unfolded to particle level and the data are compared to state-of-the-art Monte Carlo predictions, which are found to describe the data well. A new technique is proposed to utilize this dataset to extract a value of the top-quark width, inspired by recent efforts to measure the Higgs boson width using off-shell decays. A value of 1.28 ± 0.27(exp.)±0.15(theory) GeV is extracted from the ATLAS data, in good agreement with the standard model prediction. Finally, a new hardware tracking system is described for use in the upgraded ATLAS Trigger system for the high-luminosity run of the LHC."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Doctor of Philosophy (PhD)"]},{"key":"dc:format.mimetype","label":"Dc Format Mimetype","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Targeting Natural Supersymmetry With Top Quarks"]}]}],"canonical_facts":{"dc:contributor.advisor":["Elliot Lipeles"],"dc:creator":["Herwig, Theodor Christian"],"dc:date":["2023-05-17T22:58:14.000"],"dc:date.accessioned":["2023-05-22T17:42:10Z"],"dc:date.available":["2001-01-01T00:00:00Z"],"dc:date.issued":["2019"],"dc:description.abstract":["This thesis describes a search for natural supersymmetry via the production of light top squarks (stops) with the ATLAS experiment, using 13 TeV proton-proton collision data delivered by the Large Hadron Collider. A range of models is considered where the stop may decay to top quarks, b jets, and a variety of other supersymmetric particles. Stop masses as large as 950 GeV are excluded at 95% confidence level when decaying to a top quark and massless lightest supersymmetric particle (LSP). In scenarios where the LSP is a Higgsino, exclusions vary from 600 to 900 GeV depending on the relative stop branching fractions and Higgsino mass splitting. The impact of precision top-quark measurements on future searches is also discussed, including a measurement of quantum interference in top-quark production and measurement of the top-quark width. A differential mass distribution is measured in events with two charged leptons and two b-tagged jets that is sensitive to the interference property. The measurement is unfolded to particle level and the data are compared to state-of-the-art Monte Carlo predictions, which are found to describe the data well. A new technique is proposed to utilize this dataset to extract a value of the top-quark width, inspired by recent efforts to measure the Higgs boson width using off-shell decays. A value of 1.28 ± 0.27(exp.)±0.15(theory) GeV is extracted from the ATLAS data, in good agreement with the standard model prediction. Finally, a new hardware tracking system is described for use in the upgraded ATLAS Trigger system for the high-luminosity run of the LHC."],"dc:description.degree":["Doctor of Philosophy (PhD)"],"dc:format.mimetype":["application/pdf"],"dc:identifier.uri":["https://repository.upenn.edu/handle/20.500.14332/30484"],"dc:language":["en"],"dc:rights":["Theodor Christian Herwig"],"dc:title":["Targeting Natural Supersymmetry With Top Quarks"],"dc:type":["Dissertation/Thesis"]},"updated_at":"2026-07-24T03:46:32Z"}