Determining the heavy seesaw neutrino mass matrix from low-energy parameters

TL;DR

This paper investigates how symmetries can fully determine the heavy neutrino mass matrix from low-energy neutrino data, with implications for leptogenesis and collider detection.

Contribution

It introduces a framework using intra- and inter-family symmetries to constrain the seesaw sector based on observable low-energy parameters.

Findings

Leptogenesis can occur in specific parameter regions with the Dirac mass matrix equal to the up-quark mass matrix.

A charged-lepton mass matrix scenario can produce a heavy neutral lepton around 1 TeV.

Detecting such a neutral lepton at colliders would be challenging.

Abstract

We explore how the seesaw sector in neutrino mass models may be constrained through symmetries to be completely determined in terms of low-energy mass, mixing angle and CP-violating phase observables. The key ingredients are intra-family symmetries to determine the neutrino Dirac mass matrix in terms of the charged-lepton or quark mass matrices, together with inter-family or flavor symmetries to determine diagonalization matrices. Implications for leptogenesis and collider detection of heavy neutral leptons are discussed. We show that leptogenesis can succeed in small regions of parameter space for the case where the neutrino Dirac mass matrix equals the up-quark mass matrix. The model where the neutrino Dirac mass matrix equals the charged-lepton mass matrix can yield a heavy neutral lepton as light as about 1 TeV, but detecting such a particle will be difficult.