Neutrino Masses and Scalar Singlet Dark Matter

Abstract

We propose a simple extension of the Standard Model (SM) which has a viable dark matter (DM) candidate, as well as can explain the generation of tiny neutrino masses. The DM is an electroweak (EW) singlet scalar $S$, odd under an imposed exact $Z_2$ symmetry, interacting to SM through `Higgs-portal' coupling, while all other particles are even under $Z_2$. The model also has an EW isospin $3/2$ scalar, $\Delta$ and a pair of EW isospin vector, $\Sigma$ and $\bar{\Sigma }$, responsible for generating tiny neutrino mass via the effective dimension seven operator. Thanks to the additional interactions with $\Delta$, the scalar singlet DM $S$ survives a large region of parameter space by relic density constraints from WMAP/PLANCK and direct search bounds from updated LUX data. Constraints on the model from Large Hadron Collider (LHC) has also been discussed.

Comments: Published version in PRD with some additional references; Discussion on the discrete anomaly is included