Dirac mass matrix textures and the lightest right-handed neutrino mass scale in Type I seesaw leptogenesis

TL;DR

This paper investigates the Dirac mass matrix textures in the Type I seesaw mechanism to estimate the mass scale of the lightest right-handed neutrino, crucial for understanding neutrino masses and leptogenesis.

Contribution

It determines the necessary Dirac mass matrix textures to achieve specific right-handed neutrino mass scales in leptogenesis models.

Findings

Lightest right-handed neutrino mass scale estimated between 10^9 and 10^12 GeV.

Identifies Dirac mass matrix textures compatible with vanilla leptogenesis.

Provides constraints on neutrino mass models based on leptogenesis requirements.

Abstract

The type I seesaw mechanism is one of the leading proposed explanations for how neutrinos acquire their tiny masses. However, the mass scale of the undiscovered right-handed neutrinos required by this mechanism remains undetermined. Assuming vanilla leptogenesis in the two-flavor regime, we work backwards to find the required general textures of the Dirac mass matrix from which we determine the mass of the lightest right-handed neutrino to be around $10^9 {\rm GeV}$ to $10^{12} {\rm GeV}$.