Four Zero Neutrino Yukawa Textures in the Minimal Seesaw Framework

TL;DR

This paper explores the implications of zero textures in neutrino Yukawa couplings within the Type I seesaw model, identifying maximal textures compatible with observed neutrino mixing and analyzing their role in leptogenesis.

Contribution

It classifies all four-zero Yukawa textures in the minimal seesaw framework and examines their impact on CP violation and leptogenesis.

Findings

Four-zero textures are maximal with observed mixing.

Textures allow CP violation at low and high energies.

Parameters for leptogenesis can be derived from light neutrino data.

Abstract

We investigate, within the Type I seesaw framework, the physical implications of zero textures in the Yukawa couplings which generate the neutrino Dirac mass matrix $m_D$. It is shown that four is the maximal number of texture zeroes compatible with the observed leptonic mixing and the assumption that no neutrino mass vanishes. We classify all allowed four-zero textures of $m_D$ into two categories with three classes each. We show that the different classes, in general, admit CP violation both at low and high energies. We further present the constraints obtained for low energy physics in each case. The r\^ ole of these zero textures in establishing a connection between leptogenesis and low energy data is analysed in detail. It is shown that it is possible in all cases to completely specify the parameters relevant for leptogenesis in terms of light neutrino masses and leptonic mixing together with the unknown heavy neutrino masses.