Beyond MFV in family symmetry theories of fermion masses

TL;DR

This paper compares minimal flavour violation (MFV) with models based on family symmetries, showing that non-MFV models often predict weaker suppression of flavour-changing processes, but may still be compatible with supersymmetry and hierarchy problem solutions.

Contribution

It provides a detailed comparison between MFV and family symmetry models, highlighting differences in flavour-changing suppression and potential experimental distinctions.

Findings

Non-MFV models generally predict weaker suppression of FCNCs.

Supersymmetric family symmetry models can still align with TeV-scale superpartners.

Different family quantum numbers can help distinguish models experimentally.

Abstract

Minimal Flavour Violation (MFV) postulates that the only source of flavour changing neutral currents and CP violation, as in the Standard Model, is the CKM matrix. However it does not address the origin of fermion masses and mixing and models that do usually have a structure that goes well beyond the MFV framework. In this paper we compare the MFV predictions with those obtained in models based on spontaneously broken (horizontal) family symmetries, both Abelian and non-Abelian. The generic suppression of flavour changing processes in these models turns out to be weaker than in the MFV hypothesis. Despite this, in the supersymmetric case, the suppression may still be consistent with a solution to the hierarchy problem, with masses of superpartners below 1 TeV. A comparison of FCNC and CP violation in processes involving a variety of different family quantum numbers should be able to distinguish between various family symmetry models and models satisfying the MFV hypothesis.