Gauge/gravity dual dynamics for the strongly coupled sector of composite Higgs models

Abstract

A holographic model of chiral symmetry breaking is used to study the dynamics plus the meson and baryon spectrum of the underlying strong dynamics in composite Higgs models. The model is inspired by top-down D-brane constructions. We introduce this model by applying it to Nf = 2 QCD. We compute meson masses, decay constants and the nucleon mass. The spectrum is improved by including higher dimensional operators to reflect the UV physics of QCD. Moving to composite Higgs models, we impose perturbative running for the anomalous dimension of the quark condensate in a variety of theories with varying number of colors and flavours. We compare our results in detail to lattice simulations for the following theories: SU(2) gauge theory with two Dirac fundamentals; Sp(4) gauge theory with fundamental and sextet matter; and SU(4) gauge theory with fundamental and sextet quarks. In each case, the holographic results are encouraging since they are close to lattice results for masses and decay constants. Moreover, our models allow us to compute additional observables not yet computed on the lattice, to relax the quenched approximation and move to the precise fermion content of more realistic composite Higgs models not possible on the lattice. We also provide a new holographic description of the top partners including their masses and structure functions. With the addition of higher dimension operators, we show the top Yukawa coupling can be made of order one, to generate the observed top mass. Finally, we predict the spectrum for the full set of models with top partners proposed by Ferretti and Karateev.

Composite Higgs revealed in Higgs pair photo-production at future colliders

“…As an example, lattice calculations [40][41][42] for a QCD-like theory with 4 light flavours (to generate a composite Higgs model) and 6 or 8 heavy ones feature a 0 ++ scalar resonance with a mass lower than half of the ρ mass. This result has been found also in gravity dual theories [43,44] and more recently in holographic realisations [45][46][47].…”

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

“…In some of these papers the deformation of the geometry was determined by the backreaction of a bulk scalar field, with a profile chosen ad hoc [31-33, 36, 37]. A recent holographic analysis of composite-Higgs models, inspired by top-down constructions can be found in [39,40]. Although bottom-up studies of holographic QCD addressing the Veneziano limit exist [41], such limit does not seem to have been considered within the context of holographic composite Higgs.…”

Topological defects formation with momentum dissipation

“…This approach does not make use of any conventional mechanism of translational symmetry breaking, but instead provides an effective bulk description of a theory without momentum conservation from massive gravity. Applications of gauge/gravity duality on non-equilibrium dynamics can be found in [36][37][38][39][40][41][42][43]. Previous holographic work on KZM were carried out in [44][45][46][47][48][49][50], without any momentum dissipation in the background.…”