Sharing but not caring: dark matter and the baryon asymmetry of the universe

Nicolás Bernal,Chee Sheng Fong,Nayara Fonseca

doi:10.1088/1475-7516/2016/09/005

Abstract

We consider scenarios where Dark Matter (DM) particles carry baryon and/or lepton numbers, which can be defined if there exist operators connecting the dark to the visible sector. As a result, the DM fields become intimately linked to the Standard Model (SM) ones and can be maximally asymmetric just like the ordinary matter. In particular, we discuss minimal scenarios where the DM is a complex scalar or a Dirac fermion coupled to operators with nonzero baryon and/or lepton numbers, and that consist of only SM fields. We consider an initial asymmetry stored in either the SM or the DM sector; the main role of these operators is to properly share the asymmetry between the two sectors, in accordance with observations. After the chemical decoupling, the DM and SM sectors do not care about each other as there is only an ineffective communication between them. Once the DM mass is specified, the Wilson coefficients of these operators are fixed by the requirement of the correct transfer of the asymmetry. We study the phenomenology of this framework at colliders, direct detection and indirect detection experiments. In particular, the LHC phenomenology is very rich and can be tested in different channels such as the two same-sign leptons with two jets, monojet and monojet with a monolepton.

Highlights

Up to now there is no compelling evidence that Dark Matter (DM) communicates with the Standard Model (SM) via interactions other than gravity; and if this is all that is, the possibilities of testing DM properties in the lab are very challenging
For each DM mass mX one can solve the Boltzmann Equation (BE) and find the appropriate value for Λ in order to distribute the asymmetries of the two sectors such that the observed DM relic abundance and the baryon asymmetry are reproduced
We have considered the case where DM is a singlet under the SM gauge interactions but carries nonzero baryon and/or lepton numbers

Summary

Introduction

Up to now there is no compelling evidence that DM communicates with the SM via interactions other than gravity; and if this is all that is, the possibilities of testing DM properties in the lab are very challenging. There are hints of a deeper connection between DM and the SM baryons. Their energy densities today are of similar order, which would suggest a common mechanism for the origin of the two species: r≡. In Eq (1.1), the superscript ‘0’ denotes the value today, YB0SM = (8.66 ± 0.06) × 10−11 [2] and the third equality is due to the assumption that both. We denote YX0 = |Y∆X | Notice that the asymmetric because DM today DM scenario itself does not justify why r ∼ 1; further theoretical inputs which relate mX to mn or Y∆X to

Objectives

Results

Conclusion