Kinetic Mixing, Dark Photons and Extra Dimensions III: Brane Localized Dark Matter

TL;DR

This paper explores a simplified 5-D brane-localized dark matter model with a bulk dark photon, analyzing its phenomenology in flat and warped extra dimensions and comparing it to more complex models.

Contribution

It introduces a new setup with dark matter and dark Higgs localized on a brane, reducing model complexity while studying dark photon phenomenology in extra dimensions.

Findings

Dark matter and dark Higgs localized on a brane simplify the model.

Phenomenology varies between flat and warped extra dimensions.

Compared to previous models, this setup reduces complexity while maintaining key features.

Abstract

Extra dimensions have proven to be a very useful tool in constructing new physics models. In earlier work, we began investigating toy models for the 5-D analog of the kinetic mixing/vector portal scenario where the interactions of dark matter, taken to be, e.g., a complex scalar, with the brane-localized fields of the Standard Model (SM) are mediated by a massive $U(1)_D$ dark photon living in the bulk. These models were shown to have many novel features differentiating them from their 4-D analogs and which, in several cases, avoided some well-known 4-D model building constraints. However, these gains were obtained at the cost of the introduction of a fair amount of model complexity, e.g., dark matter Kaluza-Klein excitations. In the present paper, we consider an alternative setup wherein the dark matter and the dark Higgs, responsible for $U(1)_D$ breaking, are both localized to the 'dark' brane at the opposite end of the 5-D interval from where the SM fields are located with only the dark photon now being a 5-D field. The phenomenology of such a setup is explored for both flat and warped extra dimensions and compared to the previous more complex models.