Quasielastic Electron-Deuteron Scattering in a Hybrid Quark-Hadron Model

We study the effects of six-quark cluster and meson exchange current on quasielastic electron-deuteron scattering, using the hybrid quark-hadron model incorporating the contribution of the isoscalar meson exchange current. Our results indicate. that the final state interaction, isoscalar and isovector meson exchange currents, and six-quark cluster contribute few to the quasielastic peak. However, they affect the extracted neutron electromagnetic form factors to some extent.     

Classical Scattering in the Covariant Two-Body Coulomb Potential

The problem of two relativistically-moving pointlike particles of constant mass is undertaken in an arbitrary Lorentz frame using the classical Lagrangian mechanics of Stückelberg, Horwitz, and Piron. The particles are assumed to interact at events along their world lines at a common world time, an invariant dynamical parameter which is not in general synchronous with the particle proper time. The Lorentz-scalar interaction is assumed to be the Coulomb potential (i.e., the inverse square spacetime potential) of the spacetime event separation. The classical orbit equations are found in 1 + 1 spacetime dimensions in the hyperbolic angle coordinates for the reduced problem. The solutions to the reduced motion in these coordinates are the spacetime generalizations of the nonrelativistic Kepler solutions. and they introduce an invariant eccentricity which is a function of other known constants of the motion for the reduced problem. Solutions compatible with physical scattering are obtained by the assumption that the eccentricity is a given function of the ratio of the particle masses.     

Scattering of Two Spin-Half Particles in a Three-Dimensional Approach

Scattering of two spin- ${\frac{1}{2}}$ particles is formulated in a three-dimensional approach based on a simple three-dimensional momentum-spin basis. Both cases of identical and nonidentical particles are considered. The azimuthal behaviour of the potential and of the T-matrix elements leads to a set of integral equations for the T-matrix elements in two variables, i.e. the momentum magnitude and the scattering angle. Observables can be directly calculated from these T-matrix elements. Some symmetry relations for the T-matrix elements reduce the number of equations to be solved.     

Field-Theoretic Approach to Atomic Scattering

Scattering of two complex atomic systems has been considered in a field-theoretic way. It is observed that in this approach several deficiencies of ordinary wave mechanical theory for processes like rearrangement collisions can be remedied. The formalism is however, primarily aimed at providing results which may be useful in discussing relativistic atomic scattering of most general type.     

Covariant electrodynamics in a medium,II

The energy-momentum and angular momentum emission rates for an arbitrarily moving charge (whose speed is less than that of light in the medium) in a uniform transparent medium are calculated in manifestly covariant form. The calculations are executed for three types of stress tensor: Minkowski, Abraham, and Marx. Among other things it is found that the energy-momentum emission rates for the latter two tensors are equal and differ from that of the former. Further, the angular momentum emission rates for all three tensors are found to be equal. Only for the Marx tensor is this rate independent of the orientation of the associated asymptotic space-like surface.     

Covariant representations in a fibre bundle framework

Canonical and covariant representations of Lie groups of the semidirect product form G = N⊙K with N Abelian, are analyzed in a fibre bundle framework. We exhibit first the relationship between both kinds of representations in such framework. Two complementary methods of selecting irreducible representations from the covariant ones are developed. The first one proceeds by restriction to an invariant subspace and is exemplified in the case of massive integer spin representations of the Poincaré group. The second method takes quotients and is particularly useful when we deal with reducible but indecomposable representations. A family of stepped gauge transformations is generated when the method is used to obtain the covariant massless integer helicity representations of the Poincaré group; the electromagnetic and gravitational gauge transformations are just the first two cases of such a family.     

Kronig-Penney problem for a biparabolic potential: Quasifree particle motion

The Bloch states of a particle in a one-dimensional, periodic, biparabolic field are determined. The solutions are expressed in terms of confluent hypergeometric functions. It is shown that the first term of the Tricomi expansion for confluent hypergeometric functions represents the quasifree above-barrier motion of a particle and is identical to the exact Kronig-Penney solution for a square potential. Fiz. Tverd. Tela (St. Petersburg) 41, 1317–1319 (July 1999)     

Quasifree scattering of electrons from C

The scattering of high-energy electrons from ¹²C, accompanied by the knock-out of one proton, is studied using the Born approximation. The effects of using distorted waves for the outgoing proton and realistic wave functions for the bound states of ¹²C on the coincidence cross section are studied. The results are compared with those of simpler models and also with experiment.     

Dirac Oscillator in a Galilean Covariant Non-commutative Space

We study the Galilean Dirac oscillator in a non-commutative situation, with space-space and momentum-momentum non-commutativity. The wave equation is obtained via a ‘Galilean covariant’ approach, which consists in projecting the covariant equations from a (4,1)-dimensional manifold with light-cone coordinates, to a (3,1)-dimensional Galilean space-time. We obtain the exact wave functions and their energy levels for the plane and discuss the effects of non-commutativity.     

Scattering as a Quantum Metrology Problem: A Quantum Walk Approach

We address the scattering of a quantum particle by a one-dimensional barrier potential over a set of discrete positions. We formalize the problem as a continuous-time quantum walk on a lattice with an impurity and use the quantum Fisher information as a means to quantify the maximal possible accuracy in the estimation of the height of the barrier. We introduce suitable initial states of the walker and derive the reflection and transmission probabilities of the scattered state. We show that while the quantum Fisher information is affected by the width and central momentum of the initial wave packet, this dependency is weaker for the quantum signal-to-noise ratio. We also show that a dichotomic position measurement provides a nearly optimal detection scheme.     

Covariant derivatives of a spinor in finsler geometry

The aim of the author in the present article is to introduce covariant derivatives of a spinor into Finsler geometry and to show that such an operation is not only interesting from the purely mathematical point of view but also from the physical one since it is thus possible to extend the spinor theory of Heisenberg [1] to the Finsler space [2] (and, in particular, to the Riemann space [3]). The covariant form of the spinor theory of matter is essentially a nonlinear theory.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, Vol. 16, No. 2, pp. 43–49, February, 1973.     

Proton-Proton Virtual Bremsstrahlung in a Relativistic Covariant Model

 Lepton-pair production (virtual bremsstrahlung) in proton-proton scattering is investigated using a relativistic covariant model. The effects of negative-energy states and two-body currents are studied. These are shown to have large effects in some particular structure functions, even at the relatively small energy of a recent experiment at KVI (190 MeV). Received July 1, 1998; accepted for publication November 23, 1998     

Quasi-Elastic Electron-Deuteron Scattering and Calculation of Neutron Electromagnetic Form Factors at Q2 = 1.75 to 4.00 (GeV/c)2

Electric and Magnetic form factors of neutron are calculated via electron-deuteron scattering at 1.511 ～5.507 GeV energy using SLAC group data. Our results show that the neutron electric form factor is not equal to zero;rather it has a small value, indicating that in spite of the fact that total charge is almost neutral, there is a nonuniformcharge distribution within the neutron, and that magnetic form factor follows the dipole fit.     

Covariant Relativistic Separable Kernel Approach for Electrodisintegration of the Deuteron at High Momentum Transfer

The paper considers the electrodisintegration of the deuteron for kinematic conditions of the JLab experiment E-94-019. The calculations have been performed within the covariant Bethe?CSalpeter approach with a separable kernel of nucleon?Cnucleon interactions. The results have been obtained using the relativistic plane wave impulse approximation and compared with experimental data and other models. The influence of nucleon electromagnetic form factors has been investigated.