Refined approaches in second leptogenesis for the baryon-lepton asymmetry discrepancy

TL;DR

This paper explores how temperature-dependent heavy neutrino masses influence second leptogenesis, potentially explaining the baryon-lepton asymmetry discrepancy through altered decay channels, resonance effects, and evolving CP asymmetry.

Contribution

It introduces a refined model of second leptogenesis incorporating temperature-dependent neutrino masses and analyzes their impact on asymmetry generation.

Findings

Decay channels shift near electroweak symmetry breaking

Resonance behavior enhances scattering processes

CP asymmetry varies over cosmic history

Abstract

The temperature-dependent mass of the heavy neutrino can lead to the second leptogenesis occurring below the electroweak scale, potentially explaining the large discrepancy between baryon and lepton asymmetries. We investigate this scenario further, exploring the intricate interplay of the weak interaction processes within this framework. It includes notable shifts in the dominant decay channels of heavy neutrinos around the electroweak symmetry breaking, along with the resonance behavior of the scattering processes near the $W/Z$ mass. The $CP$ asymmetry can also vary over cosmic history due to the temperature-dependent mass, allowing the $B-L$ asymmetry generation to be amplified in the late epoch. These findings elucidate how such alterations in the dynamics of second leptogenesis contribute to addressing the observed discrepancies in baryon-lepton asymmetry.