arXiv subjects

A. V. Chukhnova

Publications and source records attributed to A. V. Chukhnova.

5 recordsLinked to original sources

arXiv2022

T violation without complex entries in lepton mixing matrix

We demonstrate that T invariance can be violated even when Pontecorvo--Maki--Nakagawa--Sakata lepton mixing matrix is real. We obtain a sufficient condition of T violation in neutrino oscillations in matter and electromagnetic field. In the two-flavor model we derive the T-violating spin-flavor transition probabilities. Then we prove that the transition probabilities for neutrino in moving medium in electromagnetic field differ from those for antineutrino in matter composed of antiparticles and electromagnetic field only in the sign of the T-violating term.

hep-ph↗

arXiv2021

Resonance enhancement of neutrino oscillations due to transition magnetic moments

We prove that a resonance enhancement of neutrino oscillations in magnetic field is possible due to transition magnetic moments and demonstrate that this resonance is strictly connected to the neutrino polarization. To study the main properties of this resonance, we obtain the probabilities of transitions between neutrino states with definite flavor and helicity in inhomogeneous electromagnetic field in the adiabatic approximation. Since the resonance is present only when the adiabaticity condition is fulfilled, we also obtain and discuss this condition.

hep-ph↗

arXiv2020

Spin rotation of neutrinos produced by compact magnetized astrophysical objects

We study the propagation of neutrinos from compact astrophysical objects with strong magnetic field, such as magnetars. Both neutrino spin rotation and oscillations in a realistic three-flavor model are taken into account. We solve the neutrino evolution equation in the magnetic field near the object and obtain the probabilities of all possible spin-flavor transitions. Assuming that neutrinos are produced in the interior of the star being in their left-handed state with electron flavor, we use these spin-flavor transition probabilities to estimate the fraction of neutrinos, which change their helicity during propagation to the Earth and thus become unobservable. Using the model of the magnetar with dipolar magnetic field, we demonstrate anisotropy in the left-handed and right-handed neutrino fluxes from such astrophysical objects.

hep-ph↗

arXiv2020

Neutrino flavor oscillations and spin rotation in matter and electromagnetic field

We obtain a relativistically covariant wave equation for neutrinos in dense matter and electromagnetic field, which describes both flavor oscillations and neutrino spin rotation. Using this equation we construct a quasi-classical theory of these phenomena. We obtain the probabilities of arbitrary spin-flavor transitions assuming the external conditions to be constant. We demonstrate that the resonance behavior of the transition probabilities is possible only when the neutrino flavor states cannot be described as superpositions of the mass eigenstates. We discover that a resonance, which is similar to the Mikheev-Smirnov-Wolfenstein resonance, takes place for neutrinos in magnetic field due to the transition magnetic moments. This resonance gives an opportunity to determine, whether neutrinos are Dirac or Majorana particles.

hep-ph↗

arXiv2019

Stationary and non-stationary solutions of the evolution equation for neutrino in matter

We study solutions of the equation which describes the evolution of a neutrino propagating in dense homogeneous medium in the framework of the quantum field theory. In the two-flavor model the explicit form of Green function is obtained, and as a consequence the dispersion law for a neutrino in matter is derived. It is shown that there exist both the solutions describing the stationary states and the solutions describing the spin-flavor coherent states of the neutrino. The stationary states may be different from the mass eigenstates, and the wave function of a state with a definite flavor should be constructed as a linear combination of the wave functions of the stationary states with coefficients, which depend on the mixing angle in matter. In the ultra-relativistic limit the wave functions of the spin-flavor coherent states coincide with the solutions of the quasi-classical evolution equation. Quasi-classical approximation of the wave functions of spin-flavor coherent states is used to calculate the probabilities of transitions between neutrino states with definite flavor and helicity.

hep-ph↗