Holographic models of composite Higgs in the Veneziano limit. Part I. Bosonic sector

TL;DR

This paper develops new holographic models to analyze the non-perturbative dynamics of strongly-coupled gauge theories with many flavors, focusing on the composite Higgs scenario and the properties of bosonic states.

Contribution

It introduces bottom-up holographic models with flavor backreaction in the Veneziano limit, linking mass gap and flavor-symmetry breaking, and explores the spectrum of composite bosons.

Findings

Mass spectrum depends on scaling dimension and number of flavors.

Identifies parameter regions with a light dilaton.

Validates holographic results against lattice and NJL models.

Abstract

We study strongly-coupled, approximately scale-invariant gauge theories, which develop a mass gap in the infrared. We argue that a large number of fermion flavours is most suitable to provide an ultraviolet completion for the composite Higgs scenario. The holographic approach allows to describe the qualitative features of the non-perturbative dynamics in the Veneziano limit. We introduce new bottom-up holographic models, which incorporate the backreaction of flavour on the geometry, and show that this can correlate the mass gap to the scale of flavour-symmetry breaking. We compute the mass spectrum for the various composite bosonic states, and study its dependence on the scaling dimension of the symmetry-breaking operators, as well as on the number of flavours. The different regions with a light dilaton are critically surveyed. We carefully assess the domain of validity of the holographic approach, and compare it with lattice simulations and the Nambu--Jona-Lasinio model.