Neutrino phenomenology from leptogenesis

TL;DR

This paper explores how a hierarchical Dirac neutrino mass matrix within a type-I seesaw framework links high-scale CP violation to low-energy neutrino parameters, constraining neutrino masses and phases through leptogenesis.

Contribution

It introduces a scenario with a compact heavy neutrino spectrum that connects leptogenesis with low-energy neutrino observables, providing specific parameter ranges.

Findings

Allowed lightest neutrino mass: 0.002-0.004 eV

Dirac CP phase range: -0.90π to -0.75π

Efficient leptogenesis with a hierarchical Dirac mass matrix

Abstract

Assuming a type-I seesaw mechanism for neutrino mass generation and invoking a baryogengesis via leptogenesis scenario, we consider a reasonable hierarchical structure for Dirac neutrino mass matrix, similar to up-type quark mass matrix. These hypotheses imply a relevant connection between high scale CP violation and low energy one. By requiring a compact heavy neutrino mass spectrum, which allows to circumvent Davidson-Ibarra limit, one can obtain an efficient leptogenesis restricting the allowed region for low energy neutrino parameters. Once the oscillating parameters are taken inside a $3\sigma$ range, through the numerical resolution of the leptogenesis Boltzmann equations one gets the following allowed intervals for the lightest neutrino mass and the Dirac CP phase: $-0.90\pi<\delta<-0.75\pi$ and $m_1\sim( 0.002 - 0.004)$ eV.