Classical scale invariance in the inert doublet model

TL;DR

This paper explores a classically scale invariant version of the inert doublet model with a hidden sector, analyzing its implications for dark matter, phenomenology, and high-scale validity.

Contribution

It introduces a scale-invariant inert doublet model with a hidden sector and studies its phenomenology and high-energy behavior.

Findings

The model can produce the correct dark matter relic density.

The addition of the CW scalar and Z' gauge boson affects direct detection prospects.

Certain parameter regions remain valid up to the Planck scale.

Abstract

The inert doublet model (IDM) is a minimal extension of the Standard Model (SM) that can account for the dark matter in the universe. Naturalness arguments motivate us to study whether the model can be embedded into a theory with dynamically generated scales. In this work we study a classically scale invariant version of the IDM with a minimal hidden sector, which has a $U(1)_{\text{CW}}$ gauge symmetry and a complex scalar $\Phi$. The mass scale is generated in the hidden sector via the Coleman-Weinberg (CW) mechanism and communicated to the two Higgs doublets via portal couplings. Since the CW scalar remains light, acquires a vacuum expectation value and mixes with the SM Higgs boson, the phenomenology of this construction can be modified with respect to the traditional IDM. We analyze the impact of adding this CW scalar and the $Z'$ gauge boson on the calculation of the dark matter relic density and on the spin-independent nucleon cross section for direct detection experiments. Finally, by studying the RG equations we find regions in parameter space which remain valid all the way up to the Planck scale.