Two component WIMP-FImP dark matter model with singlet fermion, scalar and pseudo scalar

TL;DR

This paper proposes a two-component dark matter model involving a fermion and a scalar, explaining multiple astrophysical observations such as gamma-ray excess, dark matter self-interactions, and X-ray lines.

Contribution

It introduces a novel two-component dark matter framework with spontaneous CP and Z2 symmetry breaking, unifying explanations for diverse astrophysical signals.

Findings

Explains gamma-ray excess from Galactic Centre

Accounts for dark matter self-interactions in colliding clusters

Reproduces 3.55 keV X-ray line observations

Abstract

We explore a two component dark matter model with a fermion and a scalar. In this scenario the Standard Model (SM) is extended by a fermion, a scalar and an additional pseudo scalar. The fermionic component is assumed to have a global ${\rm U(1)}_{\rm DM}$ and interacts with the pseudo scalar via Yukawa interaction while a $\mathbb{Z}_2$ symmetry is imposed on the other component -- the scalar. These ensure the stability of both the dark matter components. Although the Lagrangian of the present model is CP conserving, however the CP symmetry breaks spontaneously when the pseudo scalar acquires a vacuum expectation value (VEV). The scalar component of the dark matter in the present model also develops a VEV on spontaneous breaking of the $\mathbb{Z}_2$ symmetry. Thus the various interactions of the dark sector and the SM sector are progressed through the mixing of the SM like Higgs boson, the pseudo scalar Higgs like boson and the singlet scalar boson. We show that the observed gamma ray excess from the Galactic Centre, self-interaction of dark matter from colliding clusters as well as the 3.55 keV X-ray line from Perseus, Andromeda etc. can be simultaneously explained in the present two component dark matter model.