Sterile neutrino dark matter and low scale leptogenesis from a charged scalar.

Michele Frigerio (1) , Carlos E Yaguna

1 L2C - Laboratoire Charles Coulomb

We show that novel paths to dark matter generation and baryogenesis are open when the Standard Model is extended with three sterile neutrinos $N_i$ and a charged scalar $\delta^+$. Specifically, we propose a new production mechanism for the dark matter particle --a multi-keV sterile neutrino, $N_1$-- that does not depend on the active-sterile mixing angle and does not rely on a large primordial lepton asymmetry. Instead, $N_1$ is produced, via freeze-in, by the decays of $\delta^+$ while it is in equilibrium in the early Universe. In addition, we demonstrate that, thanks to the couplings between the heavier sterile neutrinos $N_{2,3}$ and $\delta^+$, baryogenesis via leptogenesis can be realized close to the electroweak scale. The lepton asymmetry is generated either by $N_{2,3}$-decays for masses $M_{2,3}\gtrsim$ TeV, or by $N_{2,3}$-oscillations for $M_{2,3}\sim$ GeV. Experimental signatures of this scenario include an X-ray line from dark matter decays, and the direct production of $\delta^+$ at the LHC. This model thus describes a minimal, testable scenario for neutrino masses, the baryon asymmetry, and dark matter.

Domaines: Physique des Hautes Energies - Phénoménologie [hep-ph]

Michele Frigerio, Carlos E Yaguna. Sterile neutrino dark matter and low scale leptogenesis from a charged scalar.. European Physical Journal C: Particles and Fields, 2015, 75 (1), pp.31. ⟨10.1140/epjc/s10052-014-3252-1⟩. ⟨hal-01060212⟩