Composite fermions in Electroweak Symmetry Breaking

TL;DR

This paper explores the theoretical implications of composite fermions arising from strong dynamics in electroweak symmetry breaking, analyzing their roles, constraints, and phenomenology in flavor physics and collider experiments.

Contribution

It provides a detailed analysis of singlet, doublet, and triplet composite fermions, highlighting the viability of singlets and their impact on flavor and collider phenomenology.

Findings

Doublets and triplets are generally disfavoured by precision tests.

Singlet composite fermions can preserve the CKM flavor structure.

Mixing between composite and elementary fermions influences LHC phenomenology.

Abstract

If the electroweak symmetry is broken by some unspecified strong dynamics, composite fermions may exist with definite transformation properties under SU(2)_L x SU(2)_R/SU(2)_{L+R} and may play a role in giving masses by mixing to all the standard quarks and leptons. Assuming this to be the case, we analyze the role of Singlets, Doublets and Triplets in the ElectroWeak Precision Tests and in Flavour Physics. Doublets and Triplets are generically disfavoured. In the Singlet case, we specify the breaking patterns of the flavour group that allow to keep the CKM picture of flavour physics and we discuss the effects of the mixing between composite and elementary fermions. These mixings affect in particular the rather peculiar LHC phenomenology of the composite fermions.