Baryonic and Leptonic GeV Dark Matter

Abstract

We perform a systematic analysis of models with GeV-scale dark matter coupled to baryons and leptons. Such theories provide a natural framework to explain the matter-antimatter asymmetry of the universe. We find that only a few baryonic dark matter models are free from tree-level proton decay without explicitly imposing baryon number conservation. We enumerate those cases and provide a brief overview of their phenomenology. We then focus on a leptonic dark matter model for a more detailed discussion of the baryon asymmetry generation via leptogenesis, the symmetry restoration in the dark sector and the expected dark matter annihilation signals in indirect detection experiments.

Cosmological and astrophysical probes of dark baryons

“…[48], an injection of 10 −5 neutrons per baryon from χ → nγ just after 7 Be synthesis via 3 He + 4 He → 7 Be + γ (i.e. 3 × 10 2 s < t < 10 3 s or 60 keV> T > 30 keV) would burn 7 Be via the reaction 7 Be+n → 7 Li+p and bring the 7 Be+ 7 Li abundance down to the observed values. For our n 0 χ = 0.01(n 0 p + n 0 n ) scenario (that is not ruled out by CMB η b measurements), we obtain n n /n p > 10 −5 injection within t < 10 3 s if the χ lifetime τ χ 10 6 s. Unfortunately such short lifetimes are deeply excluded by excess D/H in our setup, as in many other solutions that utilize "extra neutrons" [49].…”

“…Our setup in the m χ > m n regime could potentially address the lithium problem, the long-standing discrepancy in the 7 Li abundance between standard BBN predictions and low-metallicity stars' Spite plateau measure-ments [38]: 7 Li/H = 4.7 ± 0.7 × 10 −10 , standard BBN , (1.6 ± 0.3) × 10 −10 , Spite plateau .…”

“…These values account for the fact that 7 Be created during BBN is later converted to 7 Li via electron capture. As reviewed in Ref.…”

“…New states with masses around a GeV that mix with the standard model (SM) baryons have been considered recently for a number of compelling reasons, such as the baryon asymmetry of the universe [1][2][3][4], models of dark matter [1,[5][6][7], mirror matter scenarios [8], the neutron lifetime anomaly [6,[9][10][11][12], the recent XENON1T excess [13], 21 cm cosmology [14], and general baryonnumber violating phenomenology [15,16]. In this paper we investigate the cosmological and astrophysical effects of a simple, minimal version: a single "dark baryon" χ that carries baryon number B = 1 and mixes with the neutron.…”

Gauge Baryon Number and Dibaryonic Dark Matter

“…As a consequence, even though U (1) B is spontaneously broken, the resulting theory conserves B as a global symmetry, and a singlet B = 2 scalar may become a long-lived dark-matter [6] candidate. The idea of singlet fermions and scalars with integral B and L values is not new [7], and there have been many recent studies [8,9,10,11,12].…”