Non-Unitary Mixing Matrices in Neutrino and Vector-like Quark Models

TL;DR

This paper introduces an exact parameterisation for non-unitary mixing matrices in Standard Model extensions, facilitating analysis of models with vector-like fermions or right-handed neutrinos.

Contribution

It presents a novel, exact parameterisation method tailored for non-unitary mixing matrices in extended Standard Model frameworks.

Findings

Applicable to models with vector-like quarks and right-handed neutrinos

Simplifies analysis of non-unitary mixing effects

Enhances understanding of extended fermion sectors

Abstract

This work analyses a class of extensions of the Standard Model through the lens of a novel exact parameterisation. This parameterisation is specially suitable to the analysis of extensions of the Standard Model with non-unitary mixing matrices, like models with vector-like fermions or right-handed neutrinos. The usefulness of this parameterisation is motivated with two example models: A) Standard Model with the addition of $n_u$ up and $n_d$ down singlet vector-like quarks and B) Standard Model with the addition of $n_R$ right-handed neutrinos.