Progress on Holographic Vacuum Misalignment

TL;DR

This paper advances the understanding of holographic composite-Higgs models by unifying vacuum misalignment descriptions through boundary-localised terms, demonstrating regular gravity backgrounds and natural mass hierarchies.

Contribution

It introduces a novel approach to describe vacuum misalignment holographically, incorporating boundary-localised terms to achieve regular gravity backgrounds and realistic mass spectra.

Findings

Gravity backgrounds are completely regular and smooth.

Mass spectrum of particles is free of pathologies.

A small hierarchy naturally emerges between light and heavy states.

Abstract

We summarise highlights from an ongoing research programme that aims, in the long run, at the ambitious goal of building a realistic, complete holographic composite-Higgs model. This contribution focuses on vacuum misalignment, by showing how to unify its description, as a phenomenon arising from weak coupling considerations, in the holographic description of a strongly coupled field theory in terms of a dual gravity theory. This is achieved by a non-trivial treatment of boundary-localised terms in the gravity action. The gravity backgrounds considered are completely regular and smooth. We provide numerical examples showing that the mass spectrum of particles in the four-dimensional theory is free of pathologies, and that a small hierarchy arises naturally, between the light states that, in this simplified set up, are analogous to the standard-model particles, and all the other, new composite states emerging in the strongly coupled theory.