Heavy neutrino mass scale and quark-lepton symmetry

TL;DR

This paper estimates the heavy neutrino mass scale using neutrino oscillation data and quark-lepton symmetry, finding it generally near the unification scale unless specific mass sign conditions apply.

Contribution

It introduces a method to determine the heavy neutrino mass scale based on experimental neutrino data and symmetry assumptions, highlighting conditions for intermediate scales.

Findings

Heavy neutrino mass scale is around the unification scale.

Opposite sign masses for the two lightest neutrinos can lower the scale.

The scale depends on neutrino mass hierarchy and sign assumptions.

Abstract

Assuming hierarchical neutrino masses we calculate the heavy neutrino mass scale in the seesaw mechanism from experimental data on oscillations of solar and atmospheric neutrinos and quark-lepton symmetry. The resulting scale is around or above the unification scale, unless the two lightest neutrinos have masses of opposite sign, in which case the resulting scale can be intermediate.