Warped Electroweak Breaking Without Custodial Symmetry

TL;DR

This paper introduces a novel warped 5D model with a non-AdS IR geometry that suppresses KK mode contributions to electroweak precision tests without requiring custodial symmetry, maintaining a light Higgs for unitarization.

Contribution

It presents a new warped metric approach with a singular IR geometry, avoiding the need for custodial symmetry to satisfy electroweak constraints.

Findings

KK modes can be consistent with bounds for m > 1 TeV

The model predicts a light Higgs that unitarizes the theory

Large wave function renormalization reduces precision observable impacts

Abstract

We propose an alternative to the introduction of an extra gauge (custodial) symmetry to suppress the contribution of KK modes to the T parameter in warped theories of electroweak breaking. The mechanism is based on a general class of warped 5D metrics and a Higgs propagating in the bulk. The metrics are nearly AdS in the UV region but depart from AdS in the IR region, towards where KK fluctuations are mainly localized, and have a singularity outside the slice between the UV and IR branes. This gravitational background is generated by a bulk stabilizing scalar field which triggers a natural solution to the hierarchy problem. Depending on the model parameters, gauge-boson KK modes can be consistent with present bounds on EWPT for m > 1 TeV at 95% CL. The model contains a light Higgs mode which unitarizes the four-dimensional theory. The reduction in the precision observables can be traced back to a large wave function renormalization for this mode.