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Author ORCID Identifier

https://orcid.org/0000-0002-4669-2132

AccessType

Open Access Dissertation

Document Type

dissertation

Degree Name

Doctor of Philosophy (PhD)

Degree Program

Physics

Year Degree Awarded

2023

Month Degree Awarded

September

First Advisor

Michael Ramsey-Musolf

Subject Categories

Elementary Particles and Fields and String Theory | Nuclear

Abstract

Lepton number violation (LNV) offers promising theoretical pathways to several unresolved problems in particle and nuclear physics and unveils a diverse range of phenomenology across different energy scales. TeV-scale LNV is especially relevant for both its experimental accessibility and its broad-ranging impact, making it a key area of interest for both theoretical and experimental physicists. In this thesis, we explore three distinct scenarios within the LNV research landscape. Our first analysis concerns the implications of TeV-scale LNV effects in thermal leptogenesis and its complementary sensitivity in neutrinoless double beta (0νββ) decay and collider experiments. We employed a simplified model to scrutinize the parameter space where standard thermal leptogenesis is rendered unviable, overcoming the limitations of previous effective field theory(EFT) approaches. We found that the new particle spectrum can have a decisive impact on the relative sensitivity of the 0νββ decay and collider probes. The second scenario we examined involved a class of models that, at low energies, give rise to dimension-9LNV vector operators, typically referred to as chirally suppressed in terms of their contribution to 0νββ decay. Utilizing a simplified model that generates those types of operators, we studied and compared the sensitivities of 0νββ decay experiments and LHC searches. The searches for 0νββ decay, which are here diluted by the chiral suppression of the vector operators, are found to be less constraining than the LHC searches, whose reach is increased by the assumed kinematic accessibility of the mediator particles. Lastly, in the third scenario, we conducted a thorough study of the connection of the 0νββ decay process with lepton-number-conserving (LNC) processes in the type-II seesaw scenario of the left-right symmetric model. Through the use of an EFT approach, we improved the sensitivity in 0νββ-decay experiments compared to previous studies. The results underscored that the LNC searches or measurements at high-and low-energy experiments, which are complementary to the 0νββ-decay searches, are able to assess the type-II seesaw mechanism and sensitive to a right handed doubly-charged scalar with mass up to ∼ 5TeV. Through these studies, we have demonstrated the potential of new physics at the intersection of the energy, intensity, and cosmic frontiers in addressing significant queries in particle and nuclear physics.

DOI

https://doi.org/10.7275/35774840

Creative Commons License

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.

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