47 6 v 3 3 F eb 2 00 0 Neutrino Oscillations in Electromagnetic Fields

Oscillations of neutrinos ν L ↔ ν R in presence of an arbitrary electromagnetic field are considered. We introduce the Hamiltonian for the neutrino spin evolution equation that accounts for possible effects of neutrino magnetic µ and electric ǫ dipole moments interaction with the transversal (in respect to the neutrino momentum) and also the longitudinal components of electromagnetic field. Using this Hamiltonian we predict the new type of resonance in the neutrino oscillations ν L ↔ ν R in the presence of the field of an electromagnetic wave and in combination of an electromagnetic wave and constant magnetic field. The electromagnetic properties of neutrinos are among the most interesting issues in particle physics. Studies of the neutrino electromagnetic properties could provide an important information about the structure of theoretical model of particle interaction. For instance, the discovery of the non-vanishing neutrino magnetic moment, as well as the neutrino mass, would clearly indicate that the Standard Model have to be generalized. The non-vanishing neutrino magnetic moment hase also crucial consequences in astrophysics. As it hase been shown in plenty of studies (see, for example, [1]-[17]) that have emerged during past decades, the neutrino conversions and oscillations produced under the influence of transversal constant or constant and twisting (in space) magnetic fields could be important for evolution of astrophysical object, like the Sun and neutron stars, or could result in sufficient effects while neutrinos propagate through interstellar galactic media 2. In the previously performed studies of neutrino spin precession only effects of the neutrino magnetic (or flavour transition) moment interaction with transversal constant or twisting magnetic fields were considered (see, 1 2 It should be noted here that the neutrino helicity flip could be caused not only by the interaction with an external magnetic field (or, as it is shown below with an electromagnetic wave) but also by the scattering with charged fermions in the background (see, for example, [18] and references therein)