O. S. Pavlova

On classical description of radiation from neutral fermion with anomalous magnetic moment

Abstract Electromagnetic radiation from an uncharged spin 1/2 particle with an anomalous magnetic moment moving in the classical electromagnetic external field originates from quantum spin-flip transitions. Although this process has a purely quantum nature, it was observed for certain particular external field configurations that, when quantum recoil is neglected, the radiation power corresponds to the classical radiation from an evolving magnetic dipole. We argue that this correspondence has a more general validity in the case of an unpolarized particle and derive a general formula for radiation in terms of the external field strength and its derivative. A classical dynamics of the spin is described by the Bargmann–Michel–Telegdi equation.

Solutions of the classical equation of motion for a spin in electromagnetic fields

The evolution of a charged particle spin in electromagnetic fields of a special form is investigated based on the Bargmann-Michel-Telegdi equation. For some types of nonhomogeneous fields, an exact analytic form of the dependence of the spin vector on the four-dimensional velocity of the particle is found.

Radial Schrödinger equation: The spectral problem

Using the integral transformation method involving the investigation of the Laplace transforms of wave functions, we find the discrete spectra of the radial Schrödinger equation with a confining power-growth potential and with the generalized nuclear Coulomb attracting potential. The problem is reduced to solving a system of linear algebraic equations approximately. We give the results of calculating the discrete spectra of the S-states for the Schrödinger equation with a linearly growing confining potential and the nuclear Yukawa potential.

Nuclear β decay with massive neutrino in an external electromagnetic field

beta decay in the presence of an external electromagnetic field is investigated, taking into account the non-zero neutrino rest mass. The spectrum of electrons and polarisation effects of different orientations of nuclear spin are considered. It is shown that the electromagnetic wave substantially modifies the boundaries of the spectrum of beta electrons. The results, which include an analysis of the total decay probability in intense magnetic fields, may have various astrophysical implications.

Equations of spin motion in an external field. I

Within the framework of single-particle theory for Dirac particles, quasiclassical equations of spin motion in a magnetic field are obtained. Various operators are considered for the description of the spin properties of the particles moving in the external field. As a specific example, the equations for the magnetic moment in a focusing field are solved. The resonance character of these equations is noted.

Dynamics of electron spin in undulators

The problem on the evolution of electron spin in inhomogeneous magnetic fields of special type is solved on the basis of the classical Bargmann-Michel-Telegdi equation. The results obtained are used to analyze the behavior of electron spin in magnetic undulators.

Operators of observables for a neutral particle with anomalous magnetic moment in an electromagnetic field

The explicit form of operators of kinetic momenta and spin projection for a neutral particle with an anomalous magnetic moment in constant homogeneous electromagnetic field is found. The possible applications of the obtained results in neutrino physics are considered.

Spectrum and polarization of electrons in neutron beta-decay in an electromagnetic wave field

A study is made on a polarized neutron undergoing β-decay induced by an intense electromagnetic wave. The angular distribution of electrons in the decay is obtained and their polarization is studied. A comparison is made with the decay of a moving neutron.

/tau/-lepton decay in an arbitrary plane-wave electromagnetic field

In this work we study the leptonic-decay processes of a π-meson in a field that is a superposition of a crossed field and the field of a plane electromagnetic wave. Expressions for the decay probability are obtained that take into account a non-zero neutrino mass. The dependence of the probabilities on the spin of the created lepton is investigated. The values of the parameters of the external field are indicated for which it is possible to isolate the decay process depending on the neutrino mass, which may be of interest for the solution of the problem of the existence of the neutrino mass.

Spontaneous emission by an electron in an arbitrary plane-wave electromagnetic field

On the basis of general expressions obtained for the total emission probability and the probability of a radiation transition with spin reversal of an electron moving in an arbitrary plane-wave electromagnetic field, the particular case of a plane-wave field is considered. It is shown that under certain conditions self-polarization of the electron spin is possible during the emission by an electron in a field which is the superposition of a constant crossed field and a plane, elliptically polarized, electromagnetic wave.