paper

Precision electro-weak parameters from AdS5, localized kinetic terms and anomalous dimensions

arXiv:hep-ph/0608241

Abstract

I compare the tree level estimate of the electro-weak precision parameters in two (exactly solvable) toy models of dynamical symmetry breaking in which the strong dynamics is assumed to be described by a five-dimensional (weakly coupled) gravity dual. I discuss the effect of brane-localized kinetic terms, their use as regulators for the couplings of otherwise non-normalizable modes, and the impact of a large deviation from its natural value for the scaling dimension of the background field responsible for spontaneous symmetry breaking. The latter is assumed to model the effects of walking dynamics, i.e. of a large anomalous dimension of the chiral condensate, it has a strong impact of the spectrum of spin-1 fields and, as a consequence, on the electro-weak precision parameters. The main conclusion is that models of dynamical symmetry breaking based on a large-Nc strongly interacting SU(Nc) gauge theory are compatible with precision electro-weak constraints, and produce a very distinctive signature testable at the LHC. Some of the considerations discussed are directly relevant for analogous models in the context of AdS-QCD.

40 pages

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