Constraining Minimal $U(1)_{B-L}$ model from Dark Matter Observations

TL;DR

This paper investigates a $U(1)_{B-L}$ extension of the Standard Model with a dark matter candidate, analyzing relic abundance, direct detection constraints, and gamma-ray signals to constrain the model parameters.

Contribution

It provides the first detailed analysis of dark matter relic density, direct detection limits, and gamma-ray signals within the minimal $U(1)_{B-L}$ model with a singlet scalar and right-handed neutrino.

Findings

Dark matter relic abundance matches observations near scalar resonances.

Spin-independent cross-section is below current experimental limits but testable by future experiments.

Dark matter annihilation into two photons is consistent with Fermi-LAT bounds.

Abstract

We study the $B-L$ gauge extension of the Standard Model which contains a singlet scalar and three right-handed neutrinos. The vacuum expectation value of the singlet scalar breaks the $U(1)_{B-L}$ symmetry. Here the third generation right-handed neutrino is qualified as the dark matter candidate, as an artifact of $Z_2$-charge assignment. Relic abundance of the dark matter is consistent with WMAP9 and PLANCK data, only near scalar resonances where dark matter mass is almost half of the scalar boson masses. Requiring correct relic abundance, we restrict the parameter space of the scalar mixing angle and mass of the heavy scalar boson of this model. Besides this, the maximum value of spin-independent scattering cross-section off nucleon is well-below the {\sc Xenon100} and recent LUX exclusion limits and can be probed by future {\sc Xenon1T} experiment. In addition, we compute the annihilation of the dark matter into two photon final state in detail and compare with the Fermi-LAT upper bound on $\langle\sigma v\rangle_{\gamma \gamma}$ for NFW and Einasto profile.