Gravitational Baryogenesis after Anisotropic Inflation

TL;DR

This paper investigates whether anisotropic inflation can enhance gravitational baryogenesis sufficiently to explain the observed baryon asymmetry, considering constraints from CMB observations and the gravitino problem.

Contribution

The study analyzes gravitational baryogenesis in anisotropic inflation, demonstrating that anisotropy can increase baryon asymmetry but remains insufficient to fully account for observations under current constraints.

Findings

Anisotropy enhances baryon asymmetry compared to isotropic models.

CMB constraints limit the degree of anisotropy, reducing its effectiveness.

Gravitino problem still poses a challenge in explaining baryon asymmetry.

Abstract

The gravitational baryogensis may not generate a sufficient baryon asymmetry in the standard thermal history of the Universe when we take into account the gravitino problem. Hence it has been suggested that anisotropy of the Universe can enhance the generation of the baryon asymmetry through the increase of the time change of the Ricci scalar curvature. We study the gravitational baryogenesis in the presence of anisotropy, which is produced at the end of an anisotropic inflation. Although we confirm that the generated baryon asymmetry is enhanced compared with the original isotropic cosmological model, taking into account the constraint on the anisotropy by the recent CMB observations, we find that it is still difficult to obtain the observed baryon asymmetry only through the gravitational baryogenesis without suffering from the gravitino problem.