Neutrino Spin-flavor Oscillations in Frequently Varying External Fields

We study the neutrino oscillations in presence of frequently varying external fields. The effective Hamiltonian describing the evolution of the system of the neutrinos is derived. We also examine the resonance conditions in the case of general frequently varying external fields. The neutrino spin-flavor oscillations in the combination of the constant transversal and twisting magnetic fields are considered. We also discuss the applications of the developed method to the neutrino oscillations in the magnetic fields of the Sun. For the first time the idea of neutrino oscillations was put forward in Ref. [1]. Since then many experimental and theoretical studies of neutrino oscillations have been carried out. One of the most intriguing puzzles in neutrino physics is the solar neutrino deficit. Nowadays it is experimentally established (see, e.g., Ref. [2]) that the disappearance of solar electron neutrinos can be explained by the LMA-MSW solution [3, 4]. The process of neutrino oscillations is likely to be the most reliable explanation of the solar neutrino deficit. There are several theoretical models of the solar neutrino oscillations. The best solution of the solar neutrino problem is the LMA solution. However other scenarios such as spin-flavor precession (see Refs. [5–12]) are also considered. Spin-flavor precession requires a neutrino to possess a (transitional) magnetic moment (see Refs. [5, 6, 13]). Recently the resonant neutrino spin-flavor oscillations were studied in Ref. [14] where an attempt was made to reproduce the data of the major solar neutrino experiments using the peak profiles of the solar magnetic field. In order to explain the time modulation of the observed solar neutrino flux, which is correlated with the solar magnetic activity, solar neutrinos were assumed to be converted into sterile neutrinos. The most favorable mass square difference was ∼ 10 eV. Different approach to the solar neutrino problem was made in Ref. [15]. Supposing that neutrino spin-flavor precession played a subdominant ∗E-mail: [email protected]