A possible relation between leptogenesis and PMNS phases

TL;DR

This paper introduces a novel leptogenesis scenario linking the CP phase responsible for baryogenesis directly to the low-energy PMNS phases, involving a unique mechanism called type-II leptogenesis.

Contribution

It proposes a new leptogenesis model where the CP violation originates from a single complex vacuum expectation value, connecting high-energy leptogenesis to low-energy neutrino physics.

Findings

The scenario requires electroweak symmetry to be broken during leptogenesis.

A new loop diagram involving W boson exchange dominates CP violation.

Estimate of maximum baryon asymmetry depends on PMNS phases.

Abstract

We propose a new scenario for baryogenesis through leptogenesis, where the CP phase relevant for leptogenesis is connected directly to the PMNS phase(s) in the light neutrino mixing matrix. The scenario is realized in case only one CP phase appears in the full theory, originating from the complex vacuum expextation value of a standard model singlet field. In order to realize this scheme, the electroweak symmetry is required to be broken during the leptogenesis era and a new loop diagram with an intermediate $W$ boson exchange including the low energy neutrino mixing matrix should play the dominant contribution to the CP violation for leptogenesis. In this letter, we discuss the new basic mechanism, which we call type-II leptogenesis, and give an estimate for maximally reachable baryon asymmetry depending on the PMNS phases.