Dark Matter with Dirac and Majorana Gaugino Masses

TL;DR

This paper explores a supersymmetric model with both Dirac and Majorana gaugino masses, analyzing its implications for electroweak symmetry breaking, dark matter candidates, and potential experimental signatures.

Contribution

It introduces a minimal supersymmetric extension allowing mixed Dirac and Majorana gaugino masses, detailing the effects on Higgs sector, dark matter, and collider phenomenology.

Findings

Modified Higgs quartic coupling due to adjoint scalars.

Identification of parameter space where the neutralino relic density matches WMAP.

Distinct dark matter detection signatures for different LSP compositions.

Abstract

We consider the minimal supersymmetric extension of the Standard Model allowing both Dirac and Majorana gauginos. The Dirac masses are obtained by pairing up extra chiral multiplets: a singlet S for U(1)_Y, a triplet T for SU(2) and an octet O for SU(3) with the respective gauginos. The electroweak symmetry breaking sector is modified by the couplings of the new fields S and T to the Higgs doublets. We discuss two limits: i) both the adjoint scalars are decoupled with the main effect being the modification of the Higgs quartic coupling; ii) the singlet remaining light, and due to its direct coupling to sfermions, providing a new contribution to the soft masses and inducing new decay/production channels. We discuss the LSP in this scenario; after mentioning the possibility that it may be a Dirac gravitino, we focus on the case where it is identified with the lightest neutralino, and exhibit particular values of the parameter space where the relic density is in agreement with WMAP data. This is illustrated for different scenarios where the LSP is either a bino (in which case it can be a Dirac fermion) or bino-higgsino/wino mixtures. We also point out in each case the peculiarity of the model with respect to dark matter detection experiments.