Texture Zero Neutrino Models and Their Connection with Resonant Leptogenesis

TL;DR

This paper explores how specific neutrino textures and radiative corrections involving muon and tau Yukawa couplings can generate the cosmological CP asymmetry necessary for resonant leptogenesis at low scales, linking it to neutrino CP phases.

Contribution

It introduces a model with two degenerate right-handed neutrinos and texture zero Yukawa matrices, showing how 1-loop corrections and a dimension five operator can produce sufficient baryon asymmetry at low RHN masses.

Findings

CP asymmetry can be generated via muon Yukawa coupling inclusion.

Neutrino textures with a single dimension five operator can fit observed neutrino data.

Resonant leptogenesis can occur at RHN masses as low as a few TeV to 10^7 GeV.

Abstract

Within the low scale resonant leptogenesis scenario, the cosmological CP asymmetry may arise by radiative corrections through the charged lepton Yukawa couplings. While in some cases, as one expects, decisive role is played by the $\lambda_{\tau }$ coupling, we show that in specific neutrino textures only by inclusion of the $\lambda_{\mu }$ the cosmological CP violation is generated at 1-loop level. With the purpose to relate the cosmological CP violation to the leptonic CP phase $\delta $, we consider an extension of MSSM with two right handed neutrinos (RHN), which are degenerate in mass at high scales. Together with this, we first consider two texture zero $3\times 2$ Dirac Yukawa matrices of neutrinos. These via see-saw generated neutrino mass matrices augmented by single $\Delta L=2$ dimension five ($\rm d=5$) operator give predictive neutrino sectors with calculable CP asymmetries. The latter is generated through $\lambda_{\mu , \tau }$ coupling(s) at 1-loop level. Detailed analysis of the leptogenesis is performed. We also revise some one texture zero Dirac Yukawa matrices, considered earlier, and show that addition of a single $\Delta L=2$, $\rm d=5$ entry in the neutrino mass matrices, together with newly computed 1-loop corrections to the CP asymmetries, give nice accommodation of the neutrino sector and desirable amount of the baryon asymmetry via the resonant leptogenesis even for rather low RHN masses($\sim $few TeV -- $10^7$~GeV).