Phenomenology of unification-inspired theories of physics beyond the standard model

Abstract

Phenomenology is a critical part of modern fundamental physics, and rigorous statistical methods are employed to ascertain the degree to which existing theories and new paradigms accurately describe nature. A collection of phenomenological analyses is presented that test novel extensions of the Standard Model inspired by unification against the latest experimental results. We fit a minimal model of neutrino physics that employs a Type-I seesaw mechanism against data from neutrino experiments and the baryon asymmetry of the universe, with a focus on renormalisation group evolution. Such a model is an excellent fit to data, with particular combinations of numerical parameters yielding a χ 2 ' 1.5 − 2.6 for three degrees of freedom. Through this analysis, we find that N1-dominated leptogenesis can explain the asymmetry, which imposes strict constraints on righthanded neutrino masses. Results presented enable the Littlest Seesaw model to be tested against upcoming neutrino experiments. We study CP-conserving non-minimal flavour violation in an A4×SU(5) supersymmetric grand unified theory and find that unification at high scales implies interesting correlations between flavour violating parameters across a variety of scales. By scanning over flavour violating parameters, constrained by low energy quark and lepton flavour data, we find a striking difference between results in which individual parameters are tested in isolation and those where multiple parameters are varied simultaneously. Finally, we investigate a model with vector-like fermions and a U(1)0 gauge symmetry in the context of lepton flavour observables. Contributions to electron and muon anomalous magnetic moments due to Z 0 exchange are presented and discussed. Using analytic and numerical arguments, it is shown that such a model can explain the muon magnetic moment throughout a significant portion of the parameter space while remaining consistent with the experimental constraints from lepton flavour violating decays and neutrino trident production.

More information

Identifiers

Catalogue record

Export record