Chiral oscillations in quantum field theory

TL;DR

This paper develops a quantum field theory framework to describe chiral oscillations in Dirac particles, revealing vacuum structure implications and extending to neutrino flavor oscillations.

Contribution

It introduces a quantum field theory approach to chiral oscillations, connecting them with flavor mixing and analyzing vacuum orthogonality.

Findings

Chiral charges are diagonalized by a Bogoliubov transformation.

Vacuum states for definite chirality and energy are orthogonal.

Results extend to neutrino flavor oscillations.

Abstract

Dirac particles have two intrinsic degrees-of-freedom, helicity and chirality. While helicity is conserved in time, chirality is not constant under time evolution for massive particles, yielding the phenomenon of chiral oscillations. So far, chiral oscillations have been mainly described in the framework of single particle relativistic quantum mechanics. In this paper, we present a quantum field theory approach to chiral oscillations in analogy with the one used to describe flavor mixing and oscillations. By taking the expectation value of chiral charges, we obtain the same chiral oscillation formula derived via standard relativistic quantum mechanics. We find that chiral charges are diagonalized by a Bogoliubov transformation: this implies that the vacuum for particles with definite chirality is orthogonal to the one for those with definite energy. In the case of neutrinos, our results can be further extended to include also flavor oscillations.