Gauge $SU(2)_f$ flavour transfers

TL;DR

This paper explores a novel non-abelian $SU(2)_f$ flavour gauge symmetry within the Standard Model, focusing on flavour transfer operators that evade traditional constraints and analyzing their collider and low-energy phenomenology.

Contribution

It introduces the concept of flavour transfer via a non-abelian $SU(2)_f$ gauge group and thoroughly investigates its phenomenological implications and experimental constraints.

Findings

Flavour-transfer operators are less constrained by meson oscillations.

LHC lepton-flavour violation searches are competitive with low-energy experiments.

Explicit models demonstrate viable parameter space for new gauge bosons.

Abstract

We introduce the idea of flavour transfer from a non-abelian horizontal $SU(2)_f$ flavour gauge group embedded in the Standard Model flavour structure. The new flavour vector bosons, in the mass range from the tens of GeV to multi-TeV do not induce large flavour-changing currents and meson oscillations, which usually provide the dominant constraints on this type of structure. Instead, the dominant constraints arise from "flavour-transfer" operators that we will study in details. Several explicit models are presented and their prospects are thoroughly explored, including their phenomenology in the lepton and quark sectors at colliders and lower energy experiments. We finally perform a complete numerical fit in one such scenario, showing that LHC-based lepton-flavour violating searches are competitive with intensity frontier observables.