Liu, Wei;
(2020)
Exploring B-L gauge models at the LHC and beyond.
Doctoral thesis (Ph.D), UCL.
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Abstract
Although the Standard Model of particle physics is regarded as one of the most successful physical theories, there is strong evidence indicating the existence of physics beyond the Standard Model. This includes the dark matter and dark energy problems, the matter and antimatter asymmetry problem, and the observation of neutrino mixing and masses. In this thesis, we study some of the consequence of one example of a beyond the Standard Model theory. Namely, we discuss a model based on a spontaneously broken B-L gauge symmetry. It can explain the light neutrino masses via a Type-I seesaw mechanism with heavy neutrinos. The model predicts processes which can make additional contributions to the Large Hadron Collider (LHC) measurements such as the Higgs signal strengths, and contains processes with exotic particles which can lead to multi-lepton final states in LHC searches. Besides, from the limits on the light neutrinos masses due to double beta decay experiments and cosmological observations together with the seesaw relation, the heavy neutrinos present in the model are likely to be weakly mixed to the light neutrinos thus leading to potential displaced vertex signals at the LHC. We summarise the existing limits on the model parameters, and perform three studies using LHC measurement results, the recasting of the prompt lepton final states searches and displaced vertex searches to explore the model further. These studies are able to show competitive or even better sensitivities to the current limits for certain regions of the parameter space. For example, displaced vertex searches can reach active-sterile mixing strengths of order VμN ~10^-6, compatible with light neutrino mass generation through the seesaw mechanism for heavy neutrinos with masses around 1-100 GeV.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Exploring B-L gauge models at the LHC and beyond |
| Event: | UCL |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2020. Original content in this thesis is licensed under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) Licence (https://creativecommons.org/licenses/by/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10093026 |
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