Electroweak Symmetry Breaking from a Holographic Fourth Generation

TL;DR

This paper proposes a model where a fourth fermion generation in a warped extra dimension causes electroweak symmetry breaking through fermion condensation, leading to a composite, heavy Higgs with specific phenomenological implications.

Contribution

It introduces a novel mechanism for electroweak symmetry breaking via a localized fourth generation in a holographic extra dimension, resulting in a composite Higgs and standard model Yukawa couplings from higher-dimensional operators.

Findings

Fermion localization induces electroweak symmetry breaking via condensation.

The model predicts a heavy, localized composite Higgs.

Phenomenological analysis includes electroweak constraints and LHC implications.

Abstract

We consider a model with four generations of standard model fermions propagating in an extra dimension with an AdS background metric. We show that if the zero modes of the fourth generation are highly localized towards the infrared brane, it is possible to break the electroweak symmetry via their condensation, partly driven by their interactions with the Kaluza-Klein excitations of the gauge bosons, as well as by the presence of bulk higher-dimensional operators. This dynamical mechanism results in a composite Higgs, which is highly localized and generally heavy. The localization of fermions in the five-dimensional bulk naturally leads to the standard model Yukawa couplings via the action of the bulk higher-dimensional operators, which are suppressed by the Planck scale. We obtain the spectrum of the model and explore some of its phenomenological consequences, both for electroweak precision constraints as well as at the Large Hadron Collider.