Asymmetric dark matter in early Universe chemical equilibrium always leads to an antineutrino signal

Kamada

et al. 2019

Composite asymmetric dark matter scenarios naturally explain why the dark matter mass density is comparable with the visible matter mass density. Such scenarios generically require some entropy transfer mechanism below the composite scale; otherwise, their late-time cosmology is incompatible with observations. A tiny kinetic mixing between a dark photon and the visible photon is a promising example of the low-energy portal. In this paper, we demonstrate that grand unifications in the dark and the visible sectors explain the origin of the tiny kinetic mixing. We particularly consider an ultraviolet completion of a simple composite asymmetric dark matter model, where asymmetric dark matter carries a B − L charge. In this setup, the longevity of asymmetric dark matter is explained by the B −L symmetry, while the dark matter asymmetry originates from the B − L asymmetry generated by thermal leptogenesis. In our minimal setup, the Standard Model sector and the dark sector are unified into SU (5) GUT × SU (4) DGUT gauge theories, respectively. This model generates required B − L portal operators while suppressing unwanted higher-dimensional operators that could wash out the generated B − L asymmetry.

Section: Simple Composite Adm Modelmentioning

confidence: 99%

Section: Simple Composite Adm Modelmentioning

confidence: 99%

Ultraviolet completion of a composite asymmetric dark matter model with a dark photon portal

Kamada

et al. 2019

“…For this purpose, there need to be portal interactions which connect the B − L symmetry in the two sectors. In the model in [24] (see also [43,48]), the following operators are assumed as the portal operators,…”

Section: A a Model Of Composite Admmentioning

confidence: 99%

Oscillating composite asymmetric dark matter

Nagai

et al. 2020

The asymmetric dark matter (ADM) scenario can solve the coincidence problem between the baryon and the dark matter (DM) abundance when the DM mass is of O(1) GeV. In the ADM scenarios, composite dark matter is particularly motivated, as it can naturally provide the DM mass in the O(1) GeV range and a large annihilation cross section simultaneously. In this paper, we discuss the indirect detection constraints on the composite ADM model. The portal operators connecting the B − L asymmetries in the dark and the Standard Model(SM) sectors are assumed to be generated in association with the seesaw mechanism. In this model, composite dark matter inevitably obtains a tiny Majorana mass which induces a pair-annihilation of ADM at late times.We show that the model can be efficiently tested by the searches for gamma-ray from the dwarf spheroidal galaxies. *

“…(29)] is that it leads to a decay of the dark nucleon into a pair of the dark pion and the SM neutrino. Although the predicted lifetime of the dark nucleon is much longer than the age of the Universe, the dark nucleon decay is constrained by the measurements of the neutrino flux by the Super-Kamiokande (SK) experiment, which puts the lower limit on the portal scale from below as M * 10 8.5 GeV [26] (see also Ref. [39]).…”

Section: A N C = 2 Casementioning

confidence: 99%

Composite asymmetric dark matter with a dark photon portal

Kamada

et al. 2018

Asymmetric dark matter (ADM) is an attractive framework relating the observed baryon asymmetry of the Universe to the dark matter density. A composite particle in a new strong dynamics is a promising candidate for ADM as the strong dynamics naturally explains the ADM mass in the GeV range. Its large annihilation cross section due to the strong dynamics leaves the asymmetric component to be dominant over the symmetric component. In such composite ADM scenarios, the dark sector has a relatively large entropy density in the early Universe. The large dark sector entropy results in the overclosure of the Universe or at best contradicts with the observations of the cosmic microwave background and the successful Big-Bang Nucleosynthesis. Thus, composite ADM models generically require some portal to transfer the entropy of the dark sector into the Standard Model sector. In this paper, we consider a dark photon portal with a mass in the sub-GeV range and kinetic mixing with the Standard Model photon. We investigate the viable parameter space of the dark photon in detail, which can find broad applications to dark photon portal models. We also provide a simple working example of composite ADM with a dark photon portal. Our model is compatible with thermal leptogenesis and B − L symmetry. By taking into account the derived constraints, we show that the parameter space is largely tested by direct detection experiments. *