Flavour Covariant Formalism for Resonant Leptogenesis

TL;DR

This paper introduces a comprehensive flavour-covariant formalism for Resonant Leptogenesis, capturing mixing, oscillations, and decoherence effects, and demonstrates its significance through a specific model showing substantial differences from simpler approaches.

Contribution

It develops a unified, flavour-covariant framework for RL that includes complex quantum effects often neglected in previous models.

Findings

Final lepton asymmetry varies significantly with flavour effects.

The formalism accounts for resonant mixing, oscillations, and decoherence.

Differences of up to an order of magnitude in asymmetry predictions were observed.

Abstract

We present a fully flavour-covariant formalism for transport phenomena and apply it to study the flavour-dynamics of Resonant Leptogenesis (RL). We show that this formalism provides a complete and unified description of RL, consistently accounting for three distinct physical phenomena: (i) resonant mixing and (ii) coherent oscillations between different heavy-neutrino flavours, as well as (iii) quantum decoherence effects in the charged-lepton sector. We describe the necessary emergence of higher-rank tensors in flavour space, arising from the unitarity cuts of partial self-energies. Finally, within a Resonant $\tau$-Genesis model, we illustrate the importance of this formalism by showing that the final lepton asymmetry can vary by as much as an order of magnitude between partially flavour-dependent treatments, which do not capture all of the pertinent flavour effects.