{"id":{"repo_id":"toronto-retro","oai_identifier":"oai:utoronto.scholaris.ca:1807/97028"},"canonical_url":"https://search.dev.ndltd.org/etd/toronto-retro/oai:utoronto.scholaris.ca:1807/97028","repository":{"repo_id":"toronto-retro","name":"University of Toronto","base_url":"https://utoronto.scholaris.ca/server/oai/request"},"display":{"title":"Searching for the Higgs Boson Produced in Association with a Pair of Top Quarks in Multilepton Final States Using the ATLAS Detector at the LHC","abstract":"This thesis details a search for the associated production of a Higgs boson with a pair of top quarks using final states with multiple leptonic objects. An integrated luminosity of 36.1 fb−1 of proton-proton collision data was used, collected during 2015 and 2016 at a centre-of-mass energy of √s = 13 TeV with the ATLAS detector at the LHC. The specific final state studied in this thesis is the 3l+1τ channel which includes three light leptons (electrons or muons) and one hadronically-decaying τ-lepton. The 3l+1τ channel is primarily sensitive to the Higgs boson decaying to two τ-leptons, with additional sensitivity to the H → W+W− and H → ZZ decays. The 3l+1τ channel measured a ttH signal strength of μ = 1.6 (+1.8, -1.3) with an observed (expected) significance of 1.3 (0.9) standard deviations relative to the Standard Model background-only hypothesis. The combined ttH multilepton analysis also found an excess of events above the background-only expectation corresponding to an observed (expected) significance of 4.1 (2.8) standard deviations. The combined observed ttH signal strength of μ = 1.6 (+0.5, -0.4) is compatible with the Standard Model expectation to within approximately one standard deviation. This result shows evidence for ttH production.","abstract_html":"This thesis details a search for the associated production of a Higgs boson with a pair of top quarks using final states with multiple leptonic objects. An integrated luminosity of 36.1 fb−1 of proton-proton collision data was used, collected during 2015 and 2016 at a centre-of-mass energy of √s = 13 TeV with the ATLAS detector at the LHC. The specific final state studied in this thesis is the 3l+1τ channel which includes three light leptons (electrons or muons) and one hadronically-decaying τ-lepton. The 3l+1τ channel is primarily sensitive to the Higgs boson decaying to two τ-leptons, with additional sensitivity to the H → W+W− and H → ZZ decays. The 3l+1τ channel measured a ttH signal strength of μ = 1.6 (+1.8, -1.3) with an observed (expected) significance of 1.3 (0.9) standard deviations relative to the Standard Model background-only hypothesis. The combined ttH multilepton analysis also found an excess of events above the background-only expectation corresponding to an observed (expected) significance of 4.1 (2.8) standard deviations. The combined observed ttH signal strength of μ = 1.6 (+0.5, -0.4) is compatible with the Standard Model expectation to within approximately one standard deviation. This result shows evidence for ttH production.","abstract_has_math":false,"creators":["DeMarco, David Anthony"],"institution":null,"degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":"Physics","school":null,"contributors":[],"advisors":["Orr, Robert S"],"committee_chairs":[],"committee_members":[],"year":2019,"date_issued":"2019-06","date_published":"2019-06","updated_at":"2026-07-27T21:27:56Z","subjects":["ATLAS","Boson","Higgs","LHC","Quark","Top"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/1807/97028","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Orr, Robert S"]},{"key":"dc:contributor.department","label":"Department","values":["Physics"]},{"key":"dc:creator","label":"Author","values":["DeMarco, David Anthony"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2019-06"]},{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2019-10-30T23:00:47Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2019-10-30T23:00:47Z"]},{"key":"dc:date.issued","label":"Date","values":["2019-06"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["ATLAS","Boson","Higgs","LHC","Quark","Top"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/1807/97028"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["This thesis details a search for the associated production of a Higgs boson with a pair of top quarks using final states with multiple leptonic objects. An integrated luminosity of 36.1 fb−1 of proton-proton collision data was used, collected during 2015 and 2016 at a centre-of-mass energy of √s = 13 TeV with the ATLAS detector at the LHC. The specific final state studied in this thesis is the 3l+1τ channel which includes three light leptons (electrons or muons) and one hadronically-decaying τ-lepton. The 3l+1τ channel is primarily sensitive to the Higgs boson decaying to two τ-leptons, with additional sensitivity to the H → W+W− and H → ZZ decays. The 3l+1τ channel measured a ttH signal strength of μ = 1.6 (+1.8, -1.3) with an observed (expected) significance of 1.3 (0.9) standard deviations relative to the Standard Model background-only hypothesis. The combined ttH multilepton analysis also found an excess of events above the background-only expectation corresponding to an observed (expected) significance of 4.1 (2.8) standard deviations. The combined observed ttH signal strength of μ = 1.6 (+0.5, -0.4) is compatible with the Standard Model expectation to within approximately one standard deviation. This result shows evidence for ttH production."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Ph.D."]},{"key":"dc:title","label":"Title","values":["Searching for the Higgs Boson Produced in Association with a Pair of Top Quarks in Multilepton Final States Using the ATLAS Detector at the LHC"]}]}],"canonical_facts":{"dc:contributor.advisor":["Orr, Robert S"],"dc:contributor.department":["Physics"],"dc:creator":["DeMarco, David Anthony"],"dc:date":["2019-06"],"dc:date.accessioned":["2019-10-30T23:00:47Z"],"dc:date.available":["2019-10-30T23:00:47Z"],"dc:date.issued":["2019-06"],"dc:description.abstract":["This thesis details a search for the associated production of a Higgs boson with a pair of top quarks using final states with multiple leptonic objects. An integrated luminosity of 36.1 fb−1 of proton-proton collision data was used, collected during 2015 and 2016 at a centre-of-mass energy of √s = 13 TeV with the ATLAS detector at the LHC. The specific final state studied in this thesis is the 3l+1τ channel which includes three light leptons (electrons or muons) and one hadronically-decaying τ-lepton. The 3l+1τ channel is primarily sensitive to the Higgs boson decaying to two τ-leptons, with additional sensitivity to the H → W+W− and H → ZZ decays. The 3l+1τ channel measured a ttH signal strength of μ = 1.6 (+1.8, -1.3) with an observed (expected) significance of 1.3 (0.9) standard deviations relative to the Standard Model background-only hypothesis. The combined ttH multilepton analysis also found an excess of events above the background-only expectation corresponding to an observed (expected) significance of 4.1 (2.8) standard deviations. The combined observed ttH signal strength of μ = 1.6 (+0.5, -0.4) is compatible with the Standard Model expectation to within approximately one standard deviation. This result shows evidence for ttH production."],"dc:description.degree":["Ph.D."],"dc:identifier.uri":["http://hdl.handle.net/1807/97028"],"dc:subject":["ATLAS","Boson","Higgs","LHC","Quark","Top"],"dc:title":["Searching for the Higgs Boson Produced in Association with a Pair of Top Quarks in Multilepton Final States Using the ATLAS Detector at the LHC"],"dc:type":["Thesis"]},"updated_at":"2026-07-27T21:27:56Z"}