Fermion Helicity Flip in Weak Gravitational Fields

TL;DR

This paper investigates how weak gravitational fields can cause helicity flips in massive fermions, revealing that gravity can change the spin orientation of particles with mass, unlike massless particles.

Contribution

It demonstrates that in linearized quantum gravity, massive fermions can undergo helicity flips due to gravitational interactions, a novel insight into fermion behavior in gravitational fields.

Findings

Massive fermions can have their helicity flipped by gravity.

Massless fermions preserve their helicity in gravitational fields.

Helicity flip depends on fermion mass and gravitational interaction.

Abstract

The helicity flip of a spin-${\textstyle \frac{1}{2}}$ Dirac particle interacting gravitationally with a scalar field is analyzed in the context of linearized quantum gravity. It is shown that massive fermions may have their helicity flipped by gravity, in opposition to massless fermions which preserve their helicity.