Weakly interacting dark matter and baryogenesis

TLDR

Visible and dark matter have comparable energy densities in the present Universe despite differing properties. The study proposes that the dark matter relic density, arising from a dark matter asymmetry, is fully set by the baryon asymmetry. The authors construct baryon/lepton‑number conserving models in which neutral singlet scalars decay into dark matter scalars and quarks/leptons via exotic scalar bilinears, and the dark matter scalar couples to visible matter through Higgs exchange, enabling direct detection. The model predicts a dark matter mass in the few GeV to few TeV range, with equal and opposite baryon/lepton asymmetries in the dark matter and SM sectors, and offers testable signatures at the LHC and in direct‑detection experiments.

Abstract

In the present Universe visible and dark matter contribute comparable energy density although they have different properties. This phenomenon can be explained if the dark matter relic density, originating from a dark matter asymmetry, is fully determined by the baryon asymmetry. Thus the dark matter mass is not arbitrary; rather, it becomes predictive. We realize this scenario in baryon (lepton) number conserving models where two or more neutral singlet scalars decay into two or three baryonic (leptonic) dark matter scalars, and also decay into quarks (leptons) through other on-shell and/or off-shell exotic scalar bilinears. The produced baryon (lepton) asymmetries in the dark matter scalar and in the standard model quarks (leptons) are thus equal and opposite. The dark matter mass can be predicted in a range from a few GeV to a few TeV, depending on the baryon (lepton) numbers of the decaying scalars and the dark matter scalar. The dark matter scalar can interact with the visible matter through the exchange of the standard model Higgs boson, opening a window for the dark matter direct detection experiments. These models also provide testable predictions in the searches for the exotic scalar bilinears at LHC.