Vector-like Quarks at the Origin of Light Quark Masses and Mixing

TL;DR

This paper introduces a new model with vector-like quarks and a flavor symmetry to naturally generate light quark masses and mixing, compatible with LHC constraints and FCNC limits.

Contribution

It proposes a novel flavor symmetry framework with vector-like quarks and a scalar to address the light quark mass hierarchy and mixing.

Findings

Model achieves realistic quark masses and mixing with vector-like quarks accessible at LHC.

The flavor symmetry suppresses FCNC processes to acceptable levels.

Decay channels of vector-like quarks are identified and analyzed.

Abstract

We show how a novel fine-tuning problem present in the Standard Model can be solved through the introduction of a single flavour symmetry G, together with three $Q = - 1/3$ quarks, three $Q = 2/3$ quarks, as well as a complex singlet scalar. The symmetry G is extended to the additional fields and it is an exact symmetry of the Lagrangian, only spontaneously broken by the vacuum. Specific examples are given and a phenomenological analysis of the main features of the model is presented. It is shown that even for vector-like quarks with masses accessible at the LHC, one can have realistic quark masses and mixing, while respecting the strict constraints on process arising from flavour changing neutral currents (FCNC). The vector-like quark decay channels are also described.