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

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.

Automated summary

This study focuses on strongly-coupled gauge theories with mass gap in the infrared and considers a large number of fermion flavours for ultraviolet completion in composite Higgs scenario. By using holographic approach, new models are introduced to incorporate the backreaction of flavour on geometry. The mass spectrum of composite bosonic states is computed and its dependence on symmetry-breaking operators and number of flavours is analyzed, with a critical survey on regions with light dilaton. Validity of holographic approach is carefully assessed and compared with lattice simulations and Nambu-Jona-Lasinio model.