Pseudo scalar dark matter in a generic U$(1)_X$ model

TL;DR

This paper explores a $U(1)_X$ extended Standard Model where a pseudo scalar particle, arising from spontaneous symmetry breaking, serves as a dark matter candidate, satisfying various experimental and theoretical constraints.

Contribution

The study introduces a novel $U(1)_X$ model with a pseudo scalar dark matter candidate, analyzing its phenomenology and parameter space viability.

Findings

Feasible parameter space satisfying relic density and detection constraints.

Pseudo scalar DM naturally evades direct detection bounds.

Model remains consistent with collider and neutrino oscillation data.

Abstract

We consider a $U(1)_X$ extension of the Standard Model~(SM), where the spontaneous breaking of $U(1)_X$ gauge group results in a pseudo scalar particle which is the proposed candidate for dark matter. In the model, we introduce three right-handed neutrinos~(RHNs) $N_R^i$ and two extra scalars $\Phi$, $\chi$, which are SM gauge singlets but charged under $U(1)_X$ gauge group. Right-handed neutrinos are required to have the model anomaly free and explain the neutrino oscillation data. The heaviest scalar breaks the $U(1)_X$ gauge symmetry and the other extra scalar gives a pseudo scalar DM candidate. A pseudo scalar dark matter~(DM) is an interesting candidate as it naturally evades the stringent direct detection bounds due to its coupling structure. We study the phenomenology of this pseudo-scalar DM while considering several theoretical and experimental constraints. We find that in our model, there is a feasible parameter space, which satisfies by the DM lifetime bound, relic and direct detection constraints while respecting the colliders and other bounds.