Natural Theories of Physics Beyond the Standard Model

Abstract

We study natural models of physics beyond the Standard Model with several directions in mind. Firstly we study the supersymmetric extension of the U(1)Y × U(1)B−L model. This non-minimal supersymmetric model maintains the best features of the minimal supersymmetric Standard Model, but provides several new dark matter candidates. We compare metrics of finetuning in these two models and characterise these new candidates. We then focus in particular on the superpartner of the right-handed neutrino, the right-handed sneutrino and consider methods of indirect, direct and collider detection. We then consider Z 0 signals at the LHC arising from two models, the aforementioned B − L model, as well as one originating from the group U(1)R×U(1)B−L, which comes from the breaking of SO(10). These models may be distinguished by the axial couplings in the later case leading to different forward-backward asymmetry shapes. Lastly, we consider neutrino masses and the flavour puzzle. Here we use the framework of modular symmetry to present new models of neutrino masses and mixing in addition to natural charged lepton masses. We then consider a new model scenario which also accommodates the observed quark masses and mixing angles in addition to the lepton sector, providing a natural solution to the fermion mass hierarchies.

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Identifiers

ORCID for Stefano Moretti: orcid.org/0000-0002-8601-7246

ORCID for Andrew O'bannon: orcid.org/0000-0001-7862-783X

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