Composite asymmetric dark matter with a dark photon portal

Abstract

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. *

Oscillating composite asymmetric dark matter

“…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,…”

“…In [24,25], the UV model has been proposed in which the portal operators in Eq. (7) are generated by integrating out the right-handed neutrinos,N , and the dark colored Higgs This is the reason why we need both the up-type and the down-type quarks in the dark sector.…”

“…Among various ADM scenarios, composite baryonic DM in QCD-like dynamics is particularly motivated since it can naturally provide a large annihilation cross section and the DM mass in the GeV range simultaneously [7,8,[15][16][17][18][19][20][21][22][23]. Recently, a minimal composite ADM model and its ultraviolet (UV) completion [24][25][26] have been proposed where the asymmetry generated by the thermal leptogenesis [27] (see also [28][29][30] for review) is thermally distributed between the two sectors through a portal operator associated with the seesaw mechanism [31][32][33][34][35]. The dark sector of the model consists of QCD-like dynamics and QEDlike interaction, which are called as dark QCD and dark QED, respectively.…”

Baryon-dark matter coincidence in mirrored unification

“…M DGUT of O(10 10 ) GeV or larger is compatible with the composite ADM scenario with M R 10 9 GeV for thermal leptogenesis [81]. In this [48,95,96]. Therefore, the dark baryons with the mass of O(1) GeV can be naturally realized as a consequence of the Z 2 symmetry at the high-energy scale.…”

“…SU (4) DGUT is subsequently broken down to SU (3) D ×U (1) D by Σ D at M DGUT = O(µ D ). The dark sector results in the model of a composite ADM model in [48,81].…”