Higgs Dark Matter from a Warped Extra-Dimension -- the truncated-inert-doublet model

TL;DR

This paper develops a 5D warped extra-dimensional model with a Z2 symmetry that naturally produces a dark matter candidate in the form of a stable scalar, resembling the inert doublet model, with implications for dark matter phenomenology.

Contribution

The paper constructs a novel 5D warped geometry model with Z2 symmetry that yields a dark-Higgs as a dark matter candidate, extending the inert doublet model into extra dimensions.

Findings

The dark-Higgs is stable and heavier than the SM Higgs after radiative corrections.

The model's low-energy effective theory resembles the inert two Higgs doublet model.

The dark-Higgs accounts for only a small fraction of dark matter abundance.

Abstract

We construct a 5D $\mathbb{Z}_2$-symmetric model with three D3-branes: two IR ones with negative tension located at the ends of an extra-dimensional interval and a UV-brane with positive tension placed in the middle of the interval -- IR-UV-IR model. The background solutions for this geometric setup are found without and with taking into account the backreaction of the matter fields. A 5D $SU(2)$ Higgs doublet is employed as the Goldberger-Wise stabilizing field in this geometry and solutions of the 5D coupled scalar-gravity equations are found by using the superpotential method. Within this setup we investigate the low-energy (zero-mode) effective theory for the bulk Standard Model (SM) bosonic sector. The $\mathbb{Z}_2$-even zero-modes correspond to known standard degrees of freedom, whereas the $\mathbb{Z}_2$-odd zero modes might serve as a dark sector. The effective low-energy scalar sector contains a scalar which mimics the SM Higgs boson and a second stable scalar particle (dark-Higgs) is a dark matter candidate; the latter is a component of the zero-mode of the $\mathbb{Z}_2$-odd Higgs doublet. The model that results from the $\mathbb{Z}_2$-symmetric background geometry resembles the Inert Two Higgs Doublet Model. The effective theory turns out to have an extra residual $SU(2)\times U(1)$ global symmetry that is reminiscent of an underlying 5D gauge transformation for the odd degrees of freedom. At tree level the SM Higgs and the dark-Higgs have the same mass; however, when leading radiative corrections are taken into account the dark-Higgs turns out to be heavier than the SM Higgs. Implications for dark matter are discussed; it is found that the dark-Higgs can provide only a small fraction of the observed dark matter abundance.