Scattering of electrons by a Coulomb center

New results are obtained from which it follows that systematic use of the one-to-one correspondence between a physical quantity and an operator, which permits the existence of a non-negative quantum distribution function, leads to an effective smearing of the potential and to the appearance of a form factor, i.e., to the existence of structure in the scattering center.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 16–19, April, 1980.     

Probability of creating a neutral vector boson by a fermion in an arbitrary plane-wave field

The probability is obtained of creating a neutral vector boson by a fermion in an arbitrary plane-wave electromagnetic field. The superposition of a constant crossed field and the field of a planar monochromatic wave of an elliptic polarization is considered as the correct field. Some particular cases of the indicated superposition are studied.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 53–59, July, 1990.     

Improved lower limits on neutral fermion masses

Present lower limits on the mass of a neutral fermion N coupled with full strength to an electron via the right-handed weak current are set only by the absence of the decay K⁺→Ne⁺: m(N)?0.5 GeV/c². It is shown that searches for the decays τ→ν_τNe or F→Ne, followed by N→eπ, can raise the lower bound on m(N) to well over 1 G+-eV/c² if no signal is seen in present or soon-to-be-acquired data. Estimates for the branching ratios for these processes are given. If N couples to e cos φ + μ sin φ with full strength, reference to φ may be eliminated by summing over e and μ in all final states.     

On the quantum behavior of a neutral fermion in a pseudoscalar potential barrier

In this Letter we have studied the quantum behavior of a spin half neutral fermion interacting with a pseudoscalar potential barrier in (1+1$1+1$)-dimensional spacetime. Exact solutions for the corresponding Dirac equation are obtained both for bound and scattering states. The exact energy levels are obtained from the solutions of Dirac equation. The validity of the quasi-classical quantization rule is examined. For the scattering process the transmission and reflection coefficients are exactly calculated. The absence of the Klein?s paradox is also discussed.     

Vortex-core structure in neutral fermion superfluids with population imbalance

Quantized vortex-core structure is theoretically investigated in fermion superfluids with population imbalance for two atom species of neutral atom clouds near a Feshbach resonance. In contrast with the vortex core in balance case where the quantum depletion makes a vortex visible through the density profile measurement, the vortex core is filled in and becomes less visible because the quantized discrete bound states are occupied exclusively by the majority species. Yet it is shown that the core can be visible through the minority density profile experiment using phase contrast imaging, revealing an interesting opportunity to examine low-lying fermionic core bound states unexplored so far.     

Scattering of Gaussian beam by a spheroidal particle with a spherical inclusion at the center

An analytic solution to electromagnetic scattering by a spheroidal particle having a spherical inclusion at the center, for oblique incidence of a Gaussian beam, is obtained within the framework of the generalized Lorenz–Mie theory (GLMT). By virtue of a transformation between the spheroidal and spherical vector wave functions, a theoretical procedure is developed to deal with the boundary conditions. Numerical results of the normalized differential scattering cross section are evaluated.     

Constraints to the radiative lifetime of a light neutral fermion in the galactic halo from IUE

Summary We present the negative result of a search for the radiative decay of a light neutral fermion, that might be the neutrino (if massive) or the photino, gravitationally bounded to our Galaxy. The limit obtained for the radiative lifetime of a particle of mass between 12.5 and 21.5 eV is ≈10¹⁸ years. These new data on UV background in the range (1250÷2000) ? show the presence of continuum emission and diffuse lines emission at high galactic latitude (|b ^II|>45°). The lines are identifiable with C IV, λ-1549 ? and N III, λ=1749 ?. The continuum level sharply rises at 1680 ? to the level of (314±136) photons/(cm²s sr ?) and remains nearly constant up to 2000 Å. Below 1680 Å we found no emission with an upper limit of ≈100 units. These new data are briefly discussed in comparison with the results of previous experiments and theoretical expectations. Paper presented at the Congress ?Galactic and Extragalactic Dark Matter?, Roma, 28 to 30 June 1983.     

The Hypothesis of theV−A fermion current dominance and neutral current interactions

The hypothesis of theV–A fermion current dominance is expressed through an appropriate hypercharge partitioning criterion. The application of this criterion to the standard electroweak model imposes on the Weinberg mixing angle a bound which is in excellent agreement with experiments.     

The “equivalent” potential near a center of force

On the basis of the concept of a relativistic retarding force it is concluded that there is a transformation of the equivalence of the potential of a central force in the case of strong relativism. The results obtained are applied to a potential of the form /rⁿ. It is shown that the transformation of equivalence leads to the elimination or weakening of the divergence in the case of attraction and to its displacement in the case of repulsion.In conclusion the writer wishes to thank A. M. Rodichev and E. V. Kuzmin for their valuable criticisms of this work.     

Scattering of a dipole by a dipole

The spectrum of eigenvalues of the Schrödinger equation with a dipole-dipole potential is not bounded below. An appropriate cut-off leads to a correct low energy problem. Furthermore, it is shown that in polar coordinates the corresponding Schrödinger equation is separable for two spins 1/2.     

Scattering parameters of a waveguide cross junction loaded with a metallic post in the center

In this paper, the scattering parameters of a waveguide cross junction loaded with a metallic post in the center are analyzed for the first time by using the Method of Lines. The homogeneous boundary condition of the third kind and curved boundary are introduced in the formulation. Numerical results are in good agreement with the experimental data. The scattering parameters at Ka-band and W-band of the cross junctions loaded with metallic posts of different radii are presented. It is shown from the numerical results that loaded with metallic posts is an effective means for adjusting the network parameters of the waveguide cross junction to satisfy some special requirements in the design of millimeter wave components.     

Scattering and bound states of a nonrelativistic neutral spin-1/2 particle in a magnetic field

We have investigated the scattering and bound states of a nonrelativistic spin-1/2 particle in the system ofN magnetic barriers (or magnetic wells) andN magnetic delta functions. We have studied three types of problems: tunnelling with spin, band structure and change of polarization during transmission and reflection.     

Scattering and bound states of a relativistic neutral spin-1/2 particle in a magnetic field

By using the Dirac equation we have investigated the scattering and bound states of a relativistic spin-1/2 particle in the system ofN magnetic barriers (or magnetic wells) andN magnetic delta functions. Using theM-matrix method we have studied tunnelling with spin and band structure.