Dark sector production and baryogenesis from not quite black holes

Primordial black holes have been considered attractive dark matter candidates,whereas some of the predictions rely heavily on the near-horizon physics that remains to be tested experimentally.As a concrete alternative,thermal 2-2-holes closely resemble black holes without event horizons.Being a probable endpoint of gravitational collapse,they provide a solution to the information loss problem but also naturally result in stable remnants.Previously,we have considered primordial 2-2-hole remnants as dark matter.Owing to the strong constraints from a novel phenomenon associated with remnant mergers,only small remnants with mass approximate to the Planck mass can constitute all dark matter.In this paper,we examine the scenario in which the majority of dark matter consists of particles produced by the evaporation of primordial 2-2-holes,whereas the remnant contribution is secondary.The products with sufficiently light mass may contribute to the number of relativistic degrees of freedom in the early universe,which we also calculate.Moreover,2-2-hole evaporation can produce particles that are responsible for the baryon asymmetry.We observe that baryogenesis through direct B-violating decays or through leptogenesis can both be realized.Overall,the viable parameter space for the Planck remnant scenario is similar to that of primordial black holes with Planck remnants.However,heavier remnants result in different predictions,and the viable parameter space remains large even when the remnant abundance is small.

Dark matter and baryogenesis in the Fermi-bounce curvaton mechanism

We elaborate on a toy model of matter bounce, in which the matter content is constituted by two fermion species endowed with four fermion interaction terms. We describe the curvaton mechanism that is thus generated, and then argue that one of the two fermionic species may realize baryogenesis, while the other（lighter） one is compatible with constraints on extra hot dark matter particles.

Baryogenesis in f(R, T) Gravity

We study gravitational baryogenesis in the context of f(R, T) gravity where the gravitational Lagrangian is given by a generic function of the Ricci scalar R and the trace of the stress-energy tensor T. We explore how this type of modified gravity is capable to shed light on the issue of baryon asymmetry in a successful manner. We consider various forms of baryogenesis interaction and discuss the effect of these interaction terms on the baryon to entropy ratio in this setup. We show that baryon asymmetry during the radiation era of the expanding universe can be non-zero in this framework. Then, we calculate the baryon to entropy ratio for some specific f(R, T) models and by using the observational data, we give some constraints on the parameter spaces of these models.

Dark Matter and Baryons (Surplus Quarks) Generated by Oblique Confinement of Quarks

For surplus quarks (and baryons) to emerge after Big Bang, a nonequilibrium binding and superconductor-like condensation of quark-antiquark pairs must occur before the electroweak (EW) symmetry breakdown (similar for leptons). The formerly unknown dimensionless coupling to the Ginsburg-Landau like potential and the scale parameter in the EW theory then become microscopic functions of the massive quark and antiquark fields, thus defining the matter-antimatter asymmetry and the dark matter content in the Universe at correct orders of magnitude. Thereby also the number of free parameters in the Standard Model is reduced.

Direct couplings of mimetic dark matter and their cosmological effects

The original mimetic model was proposed to take the role of dark matter. In this paper we consider possible direct interactions of mimetic dark matter with other matter in the universe, especially standard model particles such as baryons and photons. By imposing shift symmetry, the mimetic dark matter field can only have derivative couplings. We discuss the possibilities of generating baryon number asymmetry and cosmic birefringence in the universe based on the derivative couplings of mimetic dark matter to baryons and photons.