Dirac Neutrino Dark Matter

TL;DR

This paper explores heavy Dirac neutrinos as dark matter candidates, analyzing their relic density and detection prospects within models featuring extra dimensions and extended gauge symmetries, highlighting their potential stability and experimental signatures.

Contribution

It provides a model-independent analysis of Dirac neutrino dark matter, connecting their properties to extra-dimensional theories and warped GUT models, and discusses their stability and detection.

Findings

Dirac neutrinos can account for dark matter with appropriate couplings.

Extra Z' gauge bosons can evade experimental constraints by coupling mainly to third generation.

Warped models naturally produce stable Kaluza-Klein neutrino states.

Abstract

We investigate the possibility that dark matter is made of heavy Dirac neutrinos with mass in the range [O(1) GeV- a few TeV] and with suppressed but non-zero coupling to the Standard Model Z as well as a coupling to an additional Z' gauge boson. The first part of this paper provides a model-independent analysis for the relic density and direct detection in terms of four main parameters: the mass, the couplings to the Z, to the Z' and to the Higgs. These WIMP candidates arise naturally as Kaluza-Klein states in extra-dimensional models with extended electroweak gauge group SU(2)_L* SU(2)_R * U(1). They can be stable because of Kaluza-Klein parity or of other discrete symmetries related to baryon number for instance, or even, in the low mass and low coupling limits, just because of a phase-space-suppressed decay width. An interesting aspect of warped models is that the extra Z' typically couples only to the third generation, thus avoiding the usual experimental constraints. In the second part of the paper, we illustrate the situation in details in a warped GUT model.