# Baryogenesis from L-violating Higgs-doublet decay in the density-matrix formalism

## TL;DR

This paper analyzes the generation of baryon asymmetry through Higgs doublet decay into right-handed neutrinos using the density-matrix formalism, highlighting the significance of lepton-number violating processes across various parameter spaces.

## Contribution

It introduces a detailed density-matrix approach to compute baryogenesis from Higgs decay, emphasizing the importance of lepton-number violation beyond high-scale leptogenesis.

## Key findings

- Lepton-number violating decay significantly contributes to baryon asymmetry.
- The process remains relevant for right-handed neutrino masses in the GeV range.
- Strong washout effects are milder for lepton-number violating decay compared to flavor oscillations.

## Abstract

We compute in the density-matrix formalism the baryon asymmetry generated by the decay of the Higgs doublet into a right-handed (RH) neutrino and a Standard Model lepton. The emphasis is put on the baryon asymmetry produced by the total lepton-number violating decay. From the derivation of the corresponding evolution equations, and from their integration, we find that this contribution is fully relevant for large parts of the parameter space. This confirms the results found recently in the CP-violating decay formalism with thermal corrections and shows in particular that the lepton-number violating processes are important not only for high-scale leptogenesis but also when the RH-neutrino masses are in the GeV range. For large values of the Yukawa couplings, we also find that the strong washout is generically much milder for this total lepton-number violating part than for the usual RH-neutrino oscillation flavour part.