Oscillations of neutrinos $ u_L leftrightarrow u_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 interaction of neutrino magnetic $mu$ and electric $epsilon$ dipole moments with the transversal (in respect to the neutrino momentum) and also the longitudinal components of electromagnetic field. Using this Hamiltonian we predict the new types of resonances in the neutrino oscillations $ u_L leftrightarrow u_R$ in the presence of the field of an electromagnetic wave and in combination of an electromagnetic wave and constant magnetic field. The possible influence of the longitudinal magnetic field on neutrino oscillations is emphasized.
The presence of medium and external magnetic field change electromagnetic properties of neutrino. In this article the behavior of neutrino magnetic moment in electromagnetic field is considered. On the basis the Bargmann-Michel-Telegdi equation for the case of models with CP invariance and P nonconservation the new type of neutrino resonances $ u_L leftrightarrow u_R$ in the electromagnetic field is predicted.
We study spin oscillations of massive Dirac neutrinos in background matter, electromagnetic and gravitational fields. First, using the Dirac equation for a neutrino interacting with the external fields in curved spacetime, we rederive the quasiclassical equation for the neutrino spin evolution, which was proposed previously basing on principles of the general covariance. Then, we apply this result for the description of neutrino spin oscillations in nonmoving and unpolarized matter under the influence of a constant transverse magnetic field and a gravitational wave. We derive the effective Schrodinger equation for neutrino oscillations in these external fields and solve it numerically. Choosing realistic parameters of external fields, we show that the parametric resonance can take place in spin oscillations of low energy neutrinos. Some astrophysical applications are briefly discussed.
We simulate neutrino-antineutrino oscillations caused by strong magnetic fields in dense matter. With the strong magnetic fields and large neutrino magnetic moments, Majorana neutrinos can reach flavor equilibrium. We find that the flavor equilibration of neutrino-antineutrino oscillations is sensitive to the values of the baryon density and the electron fraction inside the matter. The neutrino-antineutrino oscillations are suppressed in the case of the large baryon density in neutron (proton)-rich matter. On the other hand, the flavor equilibration occurs when the electron fraction is close to $0.5$ even in the large baryon density. From the simulations, we propose a necessary condition for the equilibration of neutrino-antineutrino oscillations in dense matter. We also study whether such necessary condition is satisfied near the proto-neutron star by using results of neutrino hydrodynamic simulations of core-collapse supernovae. In our explosion model, the flavor equilibration would be possible if the magnetic field on the surface of the proto-neutron star is larger than $10^{14}$ G which is the typical value of the magnetic fields of magnetars.
After a brief history of two known types of neutrino mixing and oscillations, including neutrino spin and spin-flavour oscillations in the transversal magnetic field, we perform systematic study of a new phenomenon of neutrino spin and spin-flavour oscillations engendered by the transversal matter currents on the bases of the developed quantum treatment of the phenomenon. Possibilities for the resonance amplification of these new types of oscillations by the longitudinal matter currents and longitudinal magnetic fields are analyzed. We also consider modifications of the oscillation probabilities due to possible arbitrary orientation of the magnetic field vector ${bf B}$ and the matter velocity ${bf v}$.
In the last decades, a very important breakthrough has been brought in the elementary particle physics by the discovery of the phenomenon of the neutrino oscillations, which has shown neutrino properties beyond the Standard Model. But a full understanding of the various aspects of the neutrino oscillations is far to be achieved. In this paper the theoretical background of the neutrino oscillation phenomenon is described, referring in particular to the paradigmatic models. Then the various techniques and detectors which studied neutrinos from different sources are discussed, starting from the pioneering ones up to the detectors still in operation and to those in preparation. The physics results are finally presented adopting the same research path which has crossed this long saga. The problems not yet fixed in this field are discussed, together with the perspectives of their solutions in the near future.