{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/88000"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/88000","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"A search for the ttH (H → bb) channel at the Large Hadron Collider with the ATLAS detector using a matrix element method","abstract":"A matrix element method analysis of the Standard Model Higgs boson, produced in association with two top quarks decaying to the lepton-plus-jets channel is presented. Based on 20.3 fb−1 of √s=8 TeV data, produced at the Large Hadron Collider and collected by the ATLAS detector, this analysis utilizes multiple advanced techniques to search for tt ̄H signatures with a 125 GeV Higgs boson decaying to two b-quarks. After categorizing selected events based on their jet and b-tag multiplicities, signal rich regions are analyzed using the matrix element method. Resulting variables are then propagated to two parallel multivariate analyses utilizing Neural Networks and Boosted Decision Trees respectively. As no significant excess is found, an observed (expected) limit of 3.4 (2.2) times the Standard Model cross-section is determined at 95% confidence, using the CLs method, for the Neural Network analysis. For the Boosted Decision Tree analysis, an observed (expected) limit of 5.2 (2.7) times the Standard Model cross-section is determined at 95% confidence, using the CLs method. Corresponding unconstrained fits of the Higgs boson signal strength to the observed data result in the measured signal cross-section to Standard Model cross-section prediction of μ = 1.2 ± 1.3(total) ± 0.7(stat.) for the Neural Network analysis, and μ = 2.9 ± 1.4(total) ± 0.8(stat.) for the Boosted Decision Tree analysis.","abstract_html":"A matrix element method analysis of the Standard Model Higgs boson, produced in association with two top quarks decaying to the lepton-plus-jets channel is presented. Based on 20.3 fb−1 of √s=8 TeV data, produced at the Large Hadron Collider and collected by the ATLAS detector, this analysis utilizes multiple advanced techniques to search for tt ̄H signatures with a 125 GeV Higgs boson decaying to two b-quarks. After categorizing selected events based on their jet and b-tag multiplicities, signal rich regions are analyzed using the matrix element method. Resulting variables are then propagated to two parallel multivariate analyses utilizing Neural Networks and Boosted Decision Trees respectively. As no significant excess is found, an observed (expected) limit of 3.4 (2.2) times the Standard Model cross-section is determined at 95% confidence, using the CLs method, for the Neural Network analysis. For the Boosted Decision Tree analysis, an observed (expected) limit of 5.2 (2.7) times the Standard Model cross-section is determined at 95% confidence, using the CLs method. Corresponding unconstrained fits of the Higgs boson signal strength to the observed data result in the measured signal cross-section to Standard Model cross-section prediction of μ = 1.2 ± 1.3(total) ± 0.7(stat.) for the Neural Network analysis, and μ = 2.9 ± 1.4(total) ± 0.8(stat.) for the Boosted Decision Tree analysis.","abstract_has_math":false,"creators":["Basye, Austin Thomas"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Physics","degree_department":null,"school":null,"contributors":["Liss, Tony M.","El-Khadra, Aida X","Eckstein, James N.","Martinez Outschoorn, Verena I"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2015,"date_issued":"2015-09-29T20:38:05Z","date_published":"2015-09-29T20:38:05Z","updated_at":"2026-07-22T22:26:31Z","subjects":["Higgs Boson","Large Hadron Collider (LHC)","A Toroidal LHC Apparatus (ATLAS)","8 trillion electron volt (TeV)","ttH","H to bb","Matrix Element Method","Neural Network","Boosted Decision Tree","Standard Model"],"languages":["en"],"rights":["Copyright 2015 Austin T. 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Basye"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/88000"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["A matrix element method analysis of the Standard Model Higgs boson, produced in association with two top quarks decaying to the lepton-plus-jets channel is presented. Based on 20.3 fb−1 of √s=8 TeV data, produced at the Large Hadron Collider and collected by the ATLAS detector, this analysis utilizes multiple advanced techniques to search for tt ̄H signatures with a 125 GeV Higgs boson decaying to two b-quarks. After categorizing selected events based on their jet and b-tag multiplicities, signal rich regions are analyzed using the matrix element method. Resulting variables are then propagated to two parallel multivariate analyses utilizing Neural Networks and Boosted Decision Trees respectively. As no significant excess is found, an observed (expected) limit of 3.4 (2.2) times the Standard Model cross-section is determined at 95% confidence, using the CLs method, for the Neural Network analysis. For the Boosted Decision Tree analysis, an observed (expected) limit of 5.2 (2.7) times the Standard Model cross-section is determined at 95% confidence, using the CLs method. Corresponding unconstrained fits of the Higgs boson signal strength to the observed data result in the measured signal cross-section to Standard Model cross-section prediction of μ = 1.2 ± 1.3(total) ± 0.7(stat.) for the Neural Network analysis, and μ = 2.9 ± 1.4(total) ± 0.8(stat.) for the Boosted Decision Tree analysis.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2015-09-29 without embargo terms","The student, Austin Basye, accepted the attached license on 2015-07-06 at 11:16.","The student, Austin Basye, submitted this Dissertation for approval on 2015-07-06 at 11:43.","This Dissertation was approved for publication on 2015-07-07 at 15:38.","DSpace SAF Submission Ingestion Package generated from Vireo submission #8349 on 2015-09-29 at 13:22:07","Made available in DSpace on 2015-09-29T20:38:05Z (GMT). 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Based on 20.3 fb−1 of √s=8 TeV data, produced at the Large Hadron Collider and collected by the ATLAS detector, this analysis utilizes multiple advanced techniques to search for tt ̄H signatures with a 125 GeV Higgs boson decaying to two b-quarks. After categorizing selected events based on their jet and b-tag multiplicities, signal rich regions are analyzed using the matrix element method. Resulting variables are then propagated to two parallel multivariate analyses utilizing Neural Networks and Boosted Decision Trees respectively. As no significant excess is found, an observed (expected) limit of 3.4 (2.2) times the Standard Model cross-section is determined at 95% confidence, using the CLs method, for the Neural Network analysis. For the Boosted Decision Tree analysis, an observed (expected) limit of 5.2 (2.7) times the Standard Model cross-section is determined at 95% confidence, using the CLs method. Corresponding unconstrained fits of the Higgs boson signal strength to the observed data result in the measured signal cross-section to Standard Model cross-section prediction of μ = 1.2 ± 1.3(total) ± 0.7(stat.) for the Neural Network analysis, and μ = 2.9 ± 1.4(total) ± 0.8(stat.) for the Boosted Decision Tree analysis.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2015-09-29 without embargo terms","The student, Austin Basye, accepted the attached license on 2015-07-06 at 11:16.","The student, Austin Basye, submitted this Dissertation for approval on 2015-07-06 at 11:43.","This Dissertation was approved for publication on 2015-07-07 at 15:38.","DSpace SAF Submission Ingestion Package generated from Vireo submission #8349 on 2015-09-29 at 13:22:07","Made available in DSpace on 2015-09-29T20:38:05Z (GMT). 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