Neutrino decay of an axion in an external electromagnetic field

Switching on an external electromagnetic field opens a neutrino decay channel of a hypothetical pseudoscalar particle, an axion, which plays an important role in modern field theory. We obtain exact expressions in the one-loop approximation for the probability of the decay into a massless neutrino in a crossed fieldF and study the asymptotic behavior by the nature of the parameter . Moscow State Industrial University, Moscow. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, Vol. 42, No. 2, pp. 8–12, February, 1999.     

Synchrotron and annihilation channels for axion production in an external electromagnetic field

We consider axion formation processes in the synchrotron (e ⁻→e ⁻ a) and annihilation (e ⁻ e ⁺→a) channels in a constant crossed field F _μν F^μν=Fμν*F ^μν =0, which approximates constant fields of other configurations in the ultrarelativistic asymptotic limit. The probability and intensity of axion emission are obtained, and we analyze the energy and field asymptotics. A comparison with the characteristic neutrino channel yields the constraints on the axion mass and the energy scale for Peccei-Quinn symmetry breaking. Possible astrophysical applications are discussed. Zh. éksp. Teor. Fiz. 112, 25–31 (July 1997)     

电磁场中光子-轴子的转化微分截面

运用费曼微扰方法分别计算了在磁偶极场、电偶极场和均匀静电场及静磁场中光子转化成轴子的非极化微分截面.在电偶极场中,沿光子传播方向及其反方向上的非极化微分截面为零;而在磁偶极场中,在上述方向上通常则具有非零的微分截面,但当光子传播方向平行于磁场偶极距矢量时,该微分截面为零.在均匀的静磁场和均匀静电场中,只有在光子传播方向及其反方向上具有非零的微分截面,但后者小于前者.在轴子质量趋于零的极限条件下,上述过程和光子转化为引力子的过程表现出某些非常类似的性质. 关键词： 轴子 光子 微分截面     

Two-photon cooperative decay in a cavity in the presence of a thermalized electromagnetic field

We study the cooperative two-photon spontaneous decay of an excited atomic system in a microcavity whose size is of the order of several wavelengths of atomic radiation. We show that a thermalized electromagnetic field in the microcavity strongly affects the two-photon cooperative spontaneous emission of radiation. The increase in the rate of spontaneous cooperative decay is due to the presence of a small number of thermalized photons in a microcavity mode. At low temperatures, the two-photon absorption probability is found to be a linear function of the two-photon flux, and photon superbunching is observed. Zh. éksp. Teor. Fiz. 115, 1153–1167 (April 1999)     

Green's functions in an external electromagnetic field

The possibility is discussed of using eigenfunctions to find different propagators in quantum electrodynamics (QED) with an external electromagnetic field.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 59–64, May, 1989.The authors are grateful to B. L. Voronov and I. V. Tyutin for useful discussion of the questions examined here.     

Spinning relativistic particle in an external electromagnetic field

The Hamiltonian formulation of the motion of a spinning relativistic particle in an external electromagnetic field is considered. The approach is based on the introduction of new coordinates and their conjugated momenta to describe the spin degrees of freedom together with an appropriate set of constraints in the Dirac formulation.     

Green's function of an electron in an external electromagnetic field

New field-theoretical representations are obtained for Green's function of an electron in an external electromagnetic field, making it possible to simplify its calculation substantially.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 33–37, February, 1982.     

Radiative photino decay in models with an invisible axion

In models with an invisible axion, the lightest supersymmetric particle is likely to be the fermion superpartner of the axion, the axino. The photino decay rate into axino and photon is calculated, taking into account supersymetry-breaking effects. The resulting value of the photino lifetime can be larger by a factor ∼10³ than the value calculated in the supersymmetric limit by Kim, Masiero and Nanopoulos, which has interesting and potentially important consequences.     

Particles with variable spin in an external electromagnetic field

Using the example of interactions with an external electromagnetic field, we consider the physical basis of describing fermions with spins 1/2 by means of a system of differential equations for a set of tensor fields (the Dirac-Kähler equations).Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 69–73, September, 1985.     

Small-angle approximation for an ion beam in an external electromagnetic field

A small-angle approximation method is formulated for a curvilinear ion beam propagating in an electromagnetic field. The effects of particle velocity scatter and multiple elastic scattering on the beam path in a magnetic field, the electric field of a cylindrical capacitor, and mutually orthogonal electric and magnetic fields are considered. An analytical model for beam power compression is developed.     

Lepton-pair production by a neutrino in an external electromagnetic field

Lepton-pair production by a neutrino in an external electromagnetic field is investigated within the Standard Model. For the probability of this process, a comparatively simple exact expression is derived that is convenient for a numerical analysis.     

First-order phase transition stimulated by an external electromagnetic field

The mechanism of the influence of an external electromagnetic field upon the temperature of the first-order phase transition in BaTiO₃ is discussed in the framework of the vibronic theory of ferroelectricity. The irradiation is shown to decrease the phase transition temperature. The results are in good agreement with the experimental findings.     

Effects on planetary motion of an external electromagnetic field

By considering an uncharged mass embedded in an external electromagnetic field we show that the Einstein corrections to the Newtonian results may further be modified.     

Electroweak lepton decay in the external field of a planar electromagnetic wave with circular polarization

The process of lepton decay into a W-boson and a neutrino and decay of a W-boson into a lepton and antineutrino in the field of a plane electromagnetic wave are considered within the framework of the Weinberg-Salam model. Exact expressions in terms of the external field are obtained for the probabilities of these processes and special cases are considered.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 30–34, May, 1987.     

Nonrelativistic anyons in external electromagnetic field

The first-order, infinite-component field equations we proposed before for nonrelativistic anyons (identified with particles in the plane with noncommuting coordinates) are generalized to accommodate arbitrary background electromagnetic fields. Consistent coupling of the underlying classical system to arbitrary fields is introduced; at a critical value of the magnetic field, the particle follows a Hall-like law of motion. The corresponding quantized system reveals a hidden nonlocality if the magnetic field is inhomogeneous. In the quantum Landau problem spectral as well as state structure (finite vs. infinite) asymmetry is found. The bound and scattering states, separated by the critical magnetic field phase, behave as further, distinct phases.     

Two-photon cooperative emission in the presence of athermal electromagnetic field

The possibility of cooperative spontaneous two-photon emission of an extended radiators system and the influence of the external thermal electromagnetic field on the spontaneous emission rate, in such a system, are investigated. It is concluded that, in an external electromagnetic field, the two-photon cooperative emission rate increases significantly. The importance of this effect on the emission of gamma rays from inverted long-lived isomers triggered by X-ray thermal fields, is emphasized. This revised version was published online in August 2006 with corrections to the Cover Date.     

Monopole decay in a variable external field

The rate of monopole decay into a dyon and an electron in an inhomogeneous external electric field is calculated by semiclassical methods. Comparison is made to an earlier result where this quantity was calculated for a constant field. Experimental and cosmological tests are suggested. The text was submitted by the authors in English.     

Decrease in the probability of tritium decay in an external electric field

The probability of tritium beta decay is shown to decrease under the effect of a constant uniform external electric field on the atom. For the tritium atom, the effect is due first to the reduction of the beta-decay endpoint energy and second to the reduction of the density of vacant bound electron states at the nucleus. Both of these factors reduce the beta-decay probability: the first reduces the probability of decay to continuum electron states, while the second reduces the probability of decay to a bound state.