Towards top-down holographic composite Higgs: minimal coset from maximal supergravity

TL;DR

This paper explores a holographic model based on maximal supergravity that could serve as a calculable framework for minimal composite Higgs models, analyzing symmetry breaking, mass spectra, and potential instabilities.

Contribution

It introduces a new holographic setup with a specific coset structure from supergravity, providing detailed spectral analysis relevant for composite Higgs theories.

Findings

Confirmed existence of tachyonic instabilities near parameter space boundaries

Computed the complete mass spectrum of dual bound states

Discussed the interplay of explicit and spontaneous symmetry breaking

Abstract

Within the context of top-down holography, we study a one-parameter family of regular background solutions of maximal gauged supergravity in seven dimensions, dimensionally reduced on a 2-torus. The dual, four-dimensional confining field theory realises the global (spontaneous as well as explicit) symmetry breaking pattern SO(5)->SO(4). We compute the complete mass spectrum for the fluctuations of the 128 bosonic degrees of freedom of the five-dimensional gravity theory, which correspond to scalar, pseudoscalar, vector, axial-vector, and tensor bound states of the dual field theory, and includes particles with exotic SO(4) quantum numbers. We confirm the existence of tachyonic instabilities near the boundaries of the parameter space. We discuss the interplay between explicit and spontaneous symmetry breaking. The SO(5)/SO(4) coset might provide a first step towards the realisation of a calculable framework and ultraviolet completion of minimal composite Higgs models, if the four pseudo-Nambu-Goldstone bosons are identified with the real components of the Higgs doublet in the standard model (SM), and a subgroup of SO(4) with the SU(2)xU(1) SM gauge group. We exhibit an example with an additional localised boundary term that mimics the effect of a weakly-coupled external sector.