Phys. Rev. D 109, 075007 (2024)

We study phenomenology of a light scalar dark matter (DM). In the model, there is an inert doublet scalar and a singlet Dirac fermion $\psi$, both charged under a global $Z_2$ symmetry. The mass of the lightest inert scalar $H$ can be lighter than 10 GeV by imposing appropriate relations between three scalar quartic couplings. The lightest $Z_2$ odd particle is stable and DM. In this paper, focusing on the parameter space where $H$ is lighter than $\psi$ and is DM, we discuss DM physics related to relic density, direct detection, indirect detection, collider searches, and other cosmological observations. We clarify differences from the case where $\psi$ is instead DM, which has been focused on in previous works.

• Received 5 December 2023
• Accepted 11 March 2024

DOI:https://doi.org/10.1103/PhysRevD.109.075007

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Published by the American Physical Society