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

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 derivatives. A classical dynamics of the spin is described by the Bargmann-Michel-Telegdi equation.Comment: 6 pages,latex, v2, typos correcte

On the grounding of spin effects in theory of synchrotron radiation

The problem of the uniqueness in the introduction of spin operators in the synchrotron radiation theory is discussed. For this purpose we give the invariant spin projections on the basis of the spin projections in the rest frame. The spin equations are used to construct the integrals of motion in the presence of the external electromagnetic field.Comment: 6 pages, LATE

Beta decay in external field and neutrino mass

The results of the investigation of electromagnetic field effects on the process of beta decay are used for analyzing experimental data on direct neutrino mass search.Comment: 7 pages, 7 figures, late

Electrically neutral Dirac particles in the presence of external fields: exact solutions

In the present article we present exact solutions of the Dirac equation for electric neutral particles with anomalous electric and magnetic moments. Using the algebraic method of separation of variables, the Dirac equation is separated in cartesian, cylindrical and spherical coordinates, and exact solutions are obtained in terms of special functions.Comment: 20pp, IVIC-CFLE-93/02 (this is a version without Tex problems, the first version was corrupted

Discussion on spin-flip synchrotron radiation

Quantum spin-flip transitions are of great importance in the synchrotron radiation theory. For better understanding of the nature of this phenomenon, it is necessary to except the effects connected with the electric charge radiation from observation. This fact explains the suggested choice of the spin-flip radiation model in the form of radiation of the electric neutral Dirac-Pauli particle moving in the homogeneous magnetic field. It is known that in this case, the total radiation in the quantum theory is conditioned by spin-flip transitions. The idea is that spin-flip radiation is represented as a nonstationary process connected with spin precession. We shall shown how to construct a solution of the classical equation of the spin precession in the BMT theory having the exact solution of the Dirac-Pauli equation.Thus, one will find the connection of the quantum spin-flip transitions with classical spin precession.Comment: 4 pages, LATE

Radiative Effects in the Standard Model Extension

The possibility of radiative effects induced by the Lorentz and CPT non-invariant interaction term for fermions in the Standard Model Extension is investigated. In particular, electron-positron photo-production and photon emission by electrons and positrons are studied. The rates of these processes are calculated in the Furry picture. It is demonstrated that the rates obtained in the framework of the model adopted strongly depend on the polarization states of the particles involved. As a result, ultra-relativistic particles produced should occupy states with a preferred spin orientation, i.e., photons have the sign of polarization opposite to the sign of the effective potential, while charged particle are preferably in the state with the helicity coinciding with the sign of the effective potential. This leads to evident spatial asymmetries which may have certain consequences observable at high energy accelerators, and in astrophysical and cosmological studies.Comment: 10 pages, 2 figures, Revtex4, to appear in Phys.Rev.D, misprints are correcte