Light sterile neutrinos, dark matter, and new resonances in a U(1) extension of the MSSM

Abstract

We present ψ ′ MSSM, a model based on a U (1) ψ ′ extension of the minimal supersymmetric standard model. The gauge symmetry U (1) ψ ′ , also known as U (1)N , is a linear combination of the U (1)χ and U (1) ψ subgroups of E6. The model predicts the existence of three sterile neutrinos with masses 0.1 eV, if the U (1) ψ ′ breaking scale is of order 10 TeV. Their contribution to the effective number of neutrinos at nucleosynthesis is ∆Nν ≃ 0.29. The model can provide a variety of possible cold dark matter candidates including the lightest sterile sneutrino. If the U (1) ψ ′ breaking scale is increased to 10 3 TeV, the sterile neutrinos, which are stable on account of a Z2 symmetry, become viable warm dark matter candidates. The observed value of the standard model Higgs boson mass can be obtained with relatively light stop quarks thanks to the D-term contribution from U (1) ψ ′ . The model predicts diquark and diphoton resonances which may be found at an updated LHC. The well-known µ problem is resolved and the observed baryon asymmetry of the universe can be generated via leptogenesis. The breaking of U (1) ψ ′ produces superconducting strings that may be present in our galaxy. A U (1) R symmetry plays a key role in keeping the proton stable and providing the light sterile neutrinos.

Small-Scale Cosmology “Crisis” and Self-Interacting Right-Handed Neutrino Warm Dark Matter

“…For higher symmetry breaking scales, higher sterile neutrino masses are possible. In this way, one may be able to select the appropriate parameter regime to ensure RHN masses in the range (13), in agreement with the rest of the cosmology and particle phenomenology of the model [37].…”

“…From a theoretical point of view it would be essential to consider microscopic particle physics models that could give rise to RHN with masses in the range (13). In this respect, I mention that minimal supersymmetric extensions of the standard model based on extra U (1) groups, embedded in appropriate supergravity models, can predict light sterile neutrinos in a natural range of their parameters [37]. For instance, if the U (1) group symmetry breaking occurs at scales of order 10 TeV, then the sterile neutrino masses can be less than 0.1 eV in this model.…”