Flavour and Higgs physics near the Fermi scale

TL;DR

This paper explores the implications of new physics near the Fermi scale on flavour and Higgs phenomenology, focusing on symmetries, supersymmetry, and composite Higgs models, with an emphasis on experimental constraints and model predictions.

Contribution

It introduces a fundamental U(2)^3 symmetry in the quark sector, analyzes its phenomenological consequences, and evaluates the impact of current and future measurements on various new physics models.

Findings

U(2)^3 symmetry constrains flavour violation patterns

Current Higgs measurements limit parameter space of supersymmetric models

Electroweak and flavour constraints restrict composite Higgs models

Abstract

After a discussion of the hierarchy problem of the Fermi scale, we study the flavour and Higgs boson(s) phenomenology of new physics close to it, both in general and in the specific cases of Supersymmetry and composite Higgs models. First, we promote the approximate U(2)^3 symmetry exhibited by the quark sector of the Standard Model to be a more fundamental symmetry of Nature, and explore its phenomenological consequences from an effective field theory point of view. We also study the embedding of natural Supersymmetry within the U(2)^3 framework, focusing in particular on the pattern of flavour and CP violation in B decays. Then we consider the CP-even scalar sector of the next-to-minimal supersymmetric Standard Model. We quantify the impact of current and foreseen measurements of the Higgs boson signal strengths on the physical parameters, deriving analytical relations for this purpose, and we outline a possible overall strategy to search for the other Higgs scalars. Finally we analyze the constraints from flavour and electroweak precison tests on composite Higgs models, for different representations of the composite fermions, and comparing the case of an anarchic flavour structure to models with a U(3)^3 and a U(2)^3 flavour symmetry.