Regular Article - Theoretical Physics
Chiral oscillations in the non-relativistic regime
Max Planck Institute for the Science of Light, Staudtstr. 2, PLZ, 91058, Erlangen, Germany
2 Departamento de Física, Universidade Federal de São Carlos, P.O. Box 676, 13565-905, São Carlos, São Paulo, Brazil
3 Dipartimento di Fisica, Università degli Studi di Salerno, Via Giovanni Paolo II, 132, 84084, Fisciano, Italy
4 INFN, Sezione di Napoli, Gruppo Collegato di Salerno, 80126, Naples, Italy
Accepted: 2 May 2021
Published online: 11 May 2021
Massive Dirac particles are a superposition of left and right chiral components. Since chirality is not a conserved quantity, the free Dirac Hamiltonian evolution induces chiral quantum oscillations, a phenomenon related to the Zitterbewegung, the trembling motion of free propagating particles. While not observable for particles in relativistic dynamical regimes, chiral oscillations become relevant when the particle’s rest energy is comparable to its momentum. In this paper, we quantify the effect of chiral oscillations on the non-relativistic evolution of a particle state described as a Dirac bispinor and specialize our results to describe the interplay between chiral and flavor oscillations of non-relativistic neutrinos: we compute the time-averaged survival probability and observe an energy-dependent depletion of the quantity when compared to the standard oscillation formula. In the non-relativistic regime, this depletion due to chiral oscillations can be as large as 40. Finally, we discuss the relevance of chiral oscillations in upcoming experiments which will probe the cosmic neutrino background.
© The Author(s) 2021
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