Gravitational form factors of the neutrino

TL;DR

This paper investigates the gravitational form factors of neutrinos, revealing differences between Dirac and Majorana types under CPT and CP invariance in the weak field approximation.

Contribution

It provides a detailed analysis of the gravitational form factors for neutrinos, highlighting the distinctions between Dirac and Majorana neutrinos under symmetry constraints.

Findings

Dirac neutrinos have four gravitational form factors.

Majorana neutrinos have five gravitational form factors.

Transition form factors depend on CP parity of Majorana neutrinos.

Abstract

The gravitational properties of the neutrino is studied in the weak field approximation. By imposing the hermiticity condition, CPT and CP invariance on the \em tensor matrix element, we shown that the allowed gravitational form factors for Dirac and Majorana neutrinos are very different. In a CPT and CP invariant theory, the \em tensor for a Dirac neutrino of the same specie is characterized by four gravitational form factors. As a result of CPT invariance, the \em tensor for a Majorana neutrino of the same specie has five form factors. In a CP invariant theory, if the initial and final Majorana neutrinos have the same (opposite) CP parity, then only tensor (pseudo-tensor) type transition are allowed.