Scalar dark matter in the B-L model

TL;DR

This paper explores a scalar dark matter candidate within the B-L extension of the Standard Model, analyzing its relic density, detection prospects, and potential for multiple dark matter particles, with implications for future experiments.

Contribution

It introduces a scalar dark matter candidate stabilized by B-L charge without extra symmetries and studies its phenomenology and detection prospects in this framework.

Findings

Dark matter density can be achieved via gauge or scalar interactions.

Dark matter mass below 5 TeV if gauge interactions dominate.

Detection prospects are promising for gauge interaction-controlled dark matter.

Abstract

The B-L extension of the Standard Model requires the existence of right-handed neutrinos and naturally realizes the seesaw mechanism of neutrino mass generation. We study the possibility of explaining the dark matter in this model with an additional scalar field that is a singlet of the Standard Model but charged under $U(1)_{B-L}$. An advantage of this scenario is that the stability of the dark matter can be guaranteed by appropriately choosing its B-L charge, without the need of an extra ad hoc discrete symmetry. We investigate in detail the dark matter phenomenology of this model. We show that the observed dark matter density can be obtained via gauge or scalar interactions, and that semi-annihilations could play an important role in the latter case. The regions consistent with the dark matter density are determined in each instance and the prospects for detection in future experiments are analyzed. If dark matter annihilations are controlled by the B-L gauge interaction, the mass of the dark matter particle should lie below 5 TeV and its direct detection cross section can be easily probed by XENON1T; if instead they are controlled by scalar interactions, the dark matter mass can be much larger and the detection prospects are less certain. Finally, we show that this scenario can be readily extended to accommodate multiple dark matter particles.