We consider a class of simplifed models of dynamical electroweak symmetry breaking built in terms of their fve-dimensional weakly-coupled gravity duals, in the spirit of bottom-up holography. The sigma-model consists of two abelian gauge bosons and one real, non-charged scalar feld coupled to gravity in fve dimensions. The scalar potential is a simple exponential function of the scalar feld. The background metric resulting from solving the classical equations of motion exhibits hyperscaling violation, at least at asymptotically large values of the radial direction. We study the spectrum of scalar composite states of the putative dual feld theory by fuctuating the sigma-model scalars and gravity, and discuss in which cases we fnd a parametrically light scalar state in the spectrum. We model the spontaneous breaking of the (weakly coupled) gauge symmetry to the diagonal subgroup by the choice of IR boundary conditions. We compute the mass spectrum of spin-1 states, and the precision electroweak parameter S as a function of the hyper-scaling coeffcient. We fnd a general bound on the mass of the lightest spin-1 resonance, by requiring that the indirect bounds on the precision parameters be satisfed, that implies that precision electroweak physics excludes the possibility of a techni-rho meson with mass lighter than several TeV.
Date of this Version
Elander, Daniel & Lawrance, Robert & Piai, Maurizio. (2015). Hyperscaling violation and Electroweak Symmetry Breaking. Nuclear Physics B. 716. 10.1016/j.nuclphysb.2015.06.004.