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

Abstract

The Higgs portal of the Standard Model provides the opportunity for coupling to a very light scalar field $\varphi$ via the super-renormalizable operator $\varphi (H^{†}H)$. 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 $\varphi$ from its minimum.

Comments: 6 pages, 3 figures. References added in the revised version.