Radion-activated Higgs mechanism

We study multiscalar models of radius stabilization, with an eye toward application to novel extra-dimensional models of symmetry breaking. With inspiration from holography, we construct a multiscalar effective potential that is a function of UV-brane values of the scalar fields and that takes into account bulk gravitational backreaction. We study extrema of this potential and additionally provide a “superpotential” method for generating static solutions for the extra-dimensional geometry. We apply these methods to some simple models of the Higgs mechanism where the Higgs itself plays a nontrivial role in radius stabilization. We conclude that mass mixing of the Higgs and radion is generic unless additional symmetries are imposed. We focus on models with a moderate gap between the electroweak and Kaluza-Klein scale, as required by phenomenological constraints. We note that tuning of the Higgs mass relative to the Kaluza-Klein scale is related to various classes of tuning of 5D parameters, with different resulting spectra and phenomenologies.