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A search for tWZ production at the ATLAS experiment
The production of a single top quark in association with a W boson and a W boson (tWZ) is a rare Standard Model process that has never before been observed. The tWZ process will be a useful input into global Standard Model Effective Field Theory (SMEFT) fits due to its sensitivity to top-electrowea...
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| Format: | Thesis |
| Language: | English ENG |
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Department of Physics
2025
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| _version_ | 1867613148483158016 |
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| access_status_str | Open Access |
| author | Veltman, Alexander |
| author2 | Keaveney, James |
| author_browse | Keaveney, James Veltman, Alexander |
| author_facet | Keaveney, James Veltman, Alexander |
| author_sort | Veltman, Alexander |
| collection | Thesis |
| description | The production of a single top quark in association with a W boson and a W boson (tWZ) is a rare Standard Model process that has never before been observed. The tWZ process will be a useful input into global Standard Model Effective Field Theory (SMEFT) fits due to its sensitivity to top-electroweak SMEFT coefficients in regions of high boson and boson transverse momenta. The process is also a relevant background in other top quark related measurements, such as the ttZ¯ cross section measurement. In this thesis, a search was performed for tWZ production using 140 fb−1 of √ s=13 TeV proton-proton collision data measured using the ATLAS detector. The search targets the trilepton and tetralepton final states, where regions were defined using physics object multiplicities. Graph neural networks were employed to perform signal-background discrimination. The signal strength of tWZ production µtWZ was extracted using a profile likelihood fit with a full systematic model describing experimental and modelling uncertainties. Blinded measurements of µtWZ are shown for each decay channel using an Asimov dataset as well as a combined signal extraction across both channels. The expected significance for the measurement of tWZ was determined to be 1.34σ where the precision of the measurement was limited by both systematic and statistical sources of uncertainty. Estimations for the measurements of µtWZ for higher luminosity datasets were also investigated |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/41319 |
| institution | University of Cape Town (South Africa) |
| language | English ENG |
| last_indexed | 2026-06-10T12:31:31.816Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2025 |
| publishDateRange | 2025 |
| publishDateSort | 2025 |
| publisher | Department of Physics |
| publisherStr | Department of Physics |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/41319 A search for tWZ production at the ATLAS experiment Veltman, Alexander Keaveney, James tWZ The production of a single top quark in association with a W boson and a W boson (tWZ) is a rare Standard Model process that has never before been observed. The tWZ process will be a useful input into global Standard Model Effective Field Theory (SMEFT) fits due to its sensitivity to top-electroweak SMEFT coefficients in regions of high boson and boson transverse momenta. The process is also a relevant background in other top quark related measurements, such as the ttZ¯ cross section measurement. In this thesis, a search was performed for tWZ production using 140 fb−1 of √ s=13 TeV proton-proton collision data measured using the ATLAS detector. The search targets the trilepton and tetralepton final states, where regions were defined using physics object multiplicities. Graph neural networks were employed to perform signal-background discrimination. The signal strength of tWZ production µtWZ was extracted using a profile likelihood fit with a full systematic model describing experimental and modelling uncertainties. Blinded measurements of µtWZ are shown for each decay channel using an Asimov dataset as well as a combined signal extraction across both channels. The expected significance for the measurement of tWZ was determined to be 1.34σ where the precision of the measurement was limited by both systematic and statistical sources of uncertainty. Estimations for the measurements of µtWZ for higher luminosity datasets were also investigated 2025-04-01T09:29:15Z 2025-04-01T09:29:15Z 2024 2025-04-01T09:27:08Z Thesis / Dissertation Masters MSc http://hdl.handle.net/11427/41319 en ENG application/pdf Department of Physics Faculty of Science University of Cape Town |
| spellingShingle | tWZ Veltman, Alexander A search for tWZ production at the ATLAS experiment |
| thesis_degree_str | Master's |
| title | A search for tWZ production at the ATLAS experiment |
| title_full | A search for tWZ production at the ATLAS experiment |
| title_fullStr | A search for tWZ production at the ATLAS experiment |
| title_full_unstemmed | A search for tWZ production at the ATLAS experiment |
| title_short | A search for tWZ production at the ATLAS experiment |
| title_sort | search for twz production at the atlas experiment |
| topic | tWZ |
| url | http://hdl.handle.net/11427/41319 |
| work_keys_str_mv | AT veltmanalexander asearchfortwzproductionattheatlasexperiment AT veltmanalexander searchfortwzproductionattheatlasexperiment |