Abstract
Recently a new model of “Affleck-Dine inflation” was presented, that produces the baryon asymmetry from a complex inflaton carrying baryon number, while being consistent with constraints from the cosmic microwave background. We adapt this model such that the inflaton carries lepton number, and communicates the lepton asymmetry to the standard model baryons via quasi-Dirac heavy neutral leptons (HNLs) and sphalerons. One of these HNLs, with mass underset{sim }{<} 4.5 GeV, can be (partially) asymmetric dark matter (DM), whose asymmetry is determined by that of the baryons. Its stability is directly related to the vanishing of the lightest neutrino mass. Neutrino masses are generated by integrating out heavy sterile neutrinos whose mass is above the inflation scale. The model provides an economical origin for all of the major ingredients missing from the standard model: inflation, baryogenesis, neutrino masses, and dark matter. The HNLs can be probed in fixed-target experiments like SHiP, possibly manifesting N-overline{N} oscillations. A light singlet scalar, needed for depleting the DM symmetric component, can be discovered in beam dump experiments and searches for rare decays, possibly explaining anomalous events recently observed by the KOTO collaboration. The DM HNL is strongly constrained by direct searches, and could have a cosmologically interesting self-interaction cross section.
Highlights
Phenomena as opposed to problems of naturalness
The relic density for fully asymmetric dark matter (DM) is determined by its chemical potential, which in our framework is related to the baryon asymmetry in a deterministic way, since the DM initially has the same asymmetry as the remaining two heavy neutral leptons (HNLs)
It is interesting to construct scenarios that link the different particle physics ingredients known to be missing from the standard model, since it can lead to distinctive predictions
Summary
During inflation φ gets an asymmetry determined mostly by the couplings in eq (1.1) and to a smaller extent by the initial conditions of the inflaton, which provide the source of CP violation in the Affleck-Dine mechanism [11]. The details of asymmetry generation at the level of φ are exactly the same as discussed in ref. The difference in the present work is that the φ asymmetry is transferred to the HNLs by the decays φ → N N from the interaction (2.1). Whether reheating is perturbative or proceeds by parametric resonance is not crucial to the present discussion, where we assume that the created asymmetry results. This can always be achieved by appropriate choice of the L-violating parameter λ , for example.
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