Sub-eV scalar dark matter through the super-renormalizable Higgs portal

TL;DR

This paper explores a light scalar dark matter candidate interacting via the Higgs portal, analyzing constraints from fifth-force experiments and cosmology, and identifying conditions for detectability and fine-tuning.

Contribution

It introduces a super-renormalizable Higgs portal model for sub-eV scalar dark matter, analyzing its experimental and cosmological constraints.

Findings

Detectable fifth-force levels possible with low inflationary scales.

Model requires some fine-tuning of initial conditions.

Scalar mass remains protected against radiative corrections.

Abstract

The Higgs portal of the Standard Model provides the opportunity for coupling to a very light scalar field $\phi$ via the super-renormalizable operator $\phi(H^\dagger H)$. This allows for the existence of a very light scalar dark matter that has coherent interaction with the Standard Model particles and yet has its mass protected against radiative corrections. We analyze ensuing constraints from the fifth-force measurements, along with the cosmological requirements. We find that the detectable level of the fifth-force can be achieved in models with low inflationary scales, and certain amount of fine-tuning in the initial deviation of $\phi$ from its minimum.