Baryogenesis via Leptogenesis in an inhomogeneous universe

TL;DR

This paper explores how primordial density and metric perturbations affect baryogenesis via leptogenesis, finding that isocurvature perturbations are generated but later erased by diffusion processes.

Contribution

It analyzes the impact of early universe perturbations on baryon asymmetry generation, highlighting the evolution and suppression of baryon isocurvature perturbations.

Findings

Primordial perturbations induce baryon isocurvature fluctuations.

Diffusion processes erase these fluctuations before they impact later universe stages.

The study links early universe inhomogeneities to baryogenesis outcomes.

Abstract

We investigate the influence of primordial perturbations of the energy density and space--time metric on the generation of the lepton and baryon asymmetries. In the weak and strong washout regimes baryon isocurvature perturbations with amplitudes of the same order as those of the CMB perturbations are generated on scales of order of the respective Hubble scale. They are, however, completely washed out by baryon and photon diffusion at the later stages of the universe's evolution.