Minimal flavour deconstruction

TL;DR

This paper develops minimal, non-universal gauge theories that explain fermion flavor patterns without tiny Yukawas, using Abelian sector non-universality and symmetry breaking at high scales, consistent with experimental bounds.

Contribution

It introduces two concrete models of flavor non-universal gauge theories with minimal assumptions, explaining fermion masses and mixings without small Yukawa couplings.

Findings

Models accommodate observed flavor patterns without tiny Yukawas.

Smallest symmetry-breaking scale can be around 10 TeV, compatible with flavor constraints.

Both models incorporate neutrino masses and mixings.

Abstract

We construct two concrete examples of flavour non-universal gauge theories which, after the inclusion of all $d\leq 4$ gauge invariant operators, allow to describe the observed pattern of flavour in the charged fermion sector without any small Yukawa coupling ($y \gtrsim 0.1$). Guided by the criterium of minimality, we assume that flavour non universality is confined to the Abelian sector of the gauge group: the universal hypercharge emerges after a sequence of symmetry-breaking steps characterised by two high mass scales, $\Lambda_{[23]} < \Lambda_{[12]}$, where the second and the first fermion generations get their mass respectively. At least in one of the two models the smaller of these scales can be in the 10 TeV range, consistently with current bounds from flavour observables. Both models are extended to include as well neutrino masses and mixings.