Holographic Technidilaton and LHC searches

TL;DR

This paper explores a holographic model of dynamical electroweak symmetry breaking featuring a light dilaton, analyzing its decay properties and constraints from LHC data, with implications for composite resonance spectra.

Contribution

It provides a detailed holographic analysis of a technidilaton model, including decay rates and parameter space consistent with LHC and electroweak precision constraints.

Findings

Dilaton can have a mass of 125 GeV compatible with bounds

Decay into photons can be suppressed or enhanced depending on parameters

Heavy resonance mass splitting correlates with photon decay rate

Abstract

We analyze in detail the phenomenology of a model of dynamical electroweak symmetry breaking inspired by walking technicolor, by using the techniques of the bottom-up approach to holography. The model admits a light composite scalar state, the dilaton, in the spectrum. We focus on regions of parameter space for which the mass of such dilaton is 125 GeV, and for which the bounds on the precision electroweak parameter S are satisfied. This requires that the next-to-lightest composite state is the techni-rho meson, with a mass larger than 2.3 TeV. We compute the couplings controlling the decay rates of the dilaton to two photons and to two (real or virtual) Z and W bosons. For generic choices of the parameters, we find a suppression of the decay into heavy gauge bosons, in respect to the analog decay of the standard-model Higgs. We find a dramatic effect on the decay into photons, which can be both strongly suppressed or strongly enhanced, the latter case corresponding to the large-N regime of the dual theory. There is a correlation between this decay rate of the dilaton into photons and the mass splitting between the techni-rho meson and its axial-vector partner: if the decay is enhanced in respect to the standard-model case, then the heavy spin-1 resonances are nearly degenerate in mass, otherwise their separation in mass is comparable to the mass scale itself.