Neutrino orbital angular momentum in a plasma vortex

It is shown that an electron neutrino beam, propagating in a background plasma, can be decomposed into orbital momentum (OAM) states, similar to the OAM photon states. Coupling between different OAM neutrino states, in the presence of a plasma vortex, is considered. We show that plasma vorticity can be transferred to the neutrino beam, which is relevant to the understanding of the neutrino sources in astrophysics. Observation of neutrino OAM states could eventually become possible. (authors)