Higgs and Flavour: BSM Overview

TL;DR

This paper reviews beyond Standard Model theories near the TeV scale addressing the hierarchy and flavour puzzles, emphasizing $U(2)$-like symmetries, flavour non-universal gauge interactions, and their experimental implications.

Contribution

It provides a comprehensive overview of BSM scenarios with $U(2)$-like flavour symmetries and explores their integration with Higgs compositeness for improved naturalness.

Findings

$U(2)$-like flavour symmetries can lower new physics scale

Flavour non-universal gauge interactions can address flavour puzzles

Combining gauge structures with Higgs compositeness improves tuning

Abstract

We discuss scenarios for BSM physics near the TeV, motivated by the hierarchy problem and the flavour puzzle, and review their experimental tests at present and future colliders. Strong LHC constraints on couplings to light quarks motivate $U(2)$-like flavour symmetries as a means of lowering the new physics scale: this is demonstrated by general SMEFT analyses, and is also seen in composite Higgs solutions to the hierarchy problem. We discuss flavour non-universal gauge interactions as a possible origin for $U(2)$-like flavour symmetries which, in addition to allowing new physics to be lighter, opens up a simultaneous low-scale solution to the flavour puzzle. We focus on `flavour deconstructed' gauge interactions close to the TeV, and show how this non-universal gauge structure can be combined with Higgs compositeness in a way that better accommodates the requisite tuning in the Higgs mass.