Minimal Dirac Fermionic Dark Matter with Nonzero Magnetic Dipole Moment

TL;DR

This paper proposes a neutral Dirac fermion as a dark matter candidate with a nonzero magnetic dipole moment, analyzing its interactions, relic density constraints, and detection prospects within the electroweak scale.

Contribution

It introduces a minimal Dirac fermionic dark matter model with a nonzero magnetic dipole moment and evaluates its experimental detectability and relic density constraints.

Findings

Magnetic dipole moment constrained to 10^(-18)-10^(-17)e cm by relic density.

Candidate interacts mainly via magnetic dipole moment conserving discrete symmetries.

Current direct detection experiments do not exclude the candidate, with future detection prospects considered.

Abstract

A neutral Dirac fermion is supplied as a singlet within the context of the standard model (SM) and is considered as a dark matter (DM) candidate near electroweak scale (10-1000 GeV) with nonzero magnetic dipole moment. The Dirac particles have four different types of electromagnetic couplings (four form factors) in general. We predict that the candidate mainly interacts with SM particles through magnetic dipole moment (MDM), since MDM conserves the discrete symmetries like parity (P), time reversal (T), and charge conjugation (C) or its combination CP. The magnetic dipole moment constrained by the relic density may be as large as 10^(-18)-10^(-17)e cm. We show that the elastic scattering is due to a spin-spin interaction for the direct detection, and the candidate with mass near electroweak scale is under experimental limits of the current direct detectors, XENON10 and CDMS II. We also consider the possibility of WIMP detection in near future.