Neutrino spin-flavor oscillations derived from the mass basis

TL;DR

This paper derives the effects of constant magnetic fields on neutrino spin-flavor oscillations, providing explicit formulas for magnetic moments and analyzing how magnetic field components influence neutrino energy and mixing.

Contribution

It introduces explicit expressions for effective magnetic moments in the flavor basis and examines the impact of longitudinal magnetic fields on neutrino oscillations.

Findings

Longitudinal magnetic field shifts neutrino energy.

Longitudinal magnetic field induces additional neutrino mixing.

Derived explicit formulas for magnetic moments in flavor basis.

Abstract

We consider neutrino mixing and oscillations in presence of an arbitrary constant magnetic field with nonzero transversal $B_{\perp}$ and longitudinal $B_{\parallel}$ components with respect to the direction of neutrino propagation. The electromagnetic interaction of neutrinos is determined by diagonal and transition neutrino magnetic moments that are introduced for the neutrino mass states. Explicit expressions for the effective neutrino diagonal and transition magnetic moments for the flavor basis in terms of these values for the mass states are obtained. The effective evolution Hamiltonian for the flavor neutrino and the corresponding oscillation probability are derived. The role of the longitudinal magnetic field component is examined. In particular, it is shown that: 1) $B_{\parallel}$ coupled to the corresponding magnetic moments shifts the neutrino energy, and 2) in case of nonvanishing neutrino transition magnetic moments $B_{\parallel}$ produces an additional mixing between neutrino states, both in the mass and flavor neutrino bases.