Geometry-free neutrino masses in curved spacetime

TL;DR

This paper derives a method to determine neutrino masses in curved spacetime without detailed knowledge of wave functions or the full background geometry, focusing on boundary conditions and metric factors.

Contribution

It introduces a geometry-free approach to calculate seesaw-induced neutrino masses in curved spacetime, applicable to flat and warped extra dimensions.

Findings

Neutrino masses can be obtained without wave function details

Exact forms of seesaw masses are derived using Kaluza-Klein expansion

Mass determination depends only on boundary metric factors

Abstract

The seesaw-induced neutrino mass is discussed in a generic class of curved spacetime, including the flat and warped extra dimensions. For Majorana masses in the bulk and on the boundary, the exact forms of seesaw-induced masses are derived by using the Kaluza-Klein mode expansion and the lepton number violating correlator for bulk fermion. It is found that the neutrino mass is determined without the knowledge of wave functions and whole background geometry when the metric factor is fixed on the boundary, e.g. by solving the hierarchy problem.