652,030 research outputs found
Quantum correlated light pulses from sequential superradiance of a condensate
We discover an inherent mechanism for entanglement swap associated with
sequential superradiance from an atomic Bose-Einstein condensate. Based on
careful examinations with both analytical and numerical approaches, we conclude
that as a result of the swap mechanism, Einstein-Podolsky-Rosen (EPR)-type
quantum correlations can be detected among the scattered light pulses.Comment: 10 pages, 6 figure
Proton-Deuteron Elastic Scattering from 2.5 to 22.5 MeV
We present the results of a calculation of differential cross sections and
polarization observables for proton-deuteron elastic scattering, for proton
laboratory energies from 2.5 to 22.5 MeV. The Paris potential parametrisation
of the nuclear force is used. As solution method for the charged-composite
particle equations the 'screening and renormalisation approach' is adopted
which allows to correctly take into account the Coulomb repulsion between the
two protons. Comparison is made with the precise experimental data of Sagara et
al. [Phys. Rev. C 50, 576 (1994)] and of Sperison et al. [Nucl. Phys. A422, 81
(1984)].Comment: 24 pages, 8 eps figures, uses REVTe
Momentum Space Integral Equations for Three Charged Particles: Diagonal Kernels
It has been a long-standing question whether momentum space integral
equations of the Faddeev type are applicable to reactions of three charged
particles, in particular above the three-body threshold. For, the presence of
long-range Coulomb forces has been thought to give rise to such severe
singularities in their kernels that the latter may lack the compactness
property known to exist in the case of purely short-range interactions.
Employing the rigorously equivalent formulation in terms of an
effective-two-body theory we have proved in a preceding paper [Phys. Rev. C
{\bf 61}, 064006 (2000)] that, for all energies, the nondiagonal kernels
occurring in the integral equations which determine the transition amplitudes
for all binary collision processes, possess on and off the energy shell only
integrable singularities, provided all three particles have charges of the same
sign, i.e., all Coulomb interactions are repulsive. In the present paper we
prove that, for particles with charges of equal sign, the diagonal kernels, in
contrast, possess one, but only one, nonintegrable singularity. The latter can,
however, be isolated explicitly and dealt with in a well-defined manner. Taken
together these results imply that modified integral equations can be
formulated, with kernels that become compact after a few iterations. This
concludes the proof that standard solution methods can be used for the
calculation of all binary (i.e., (in-)elastic and rearrangement) amplitudes by
means of momentum space integral equations of the effective-two-body type.Comment: 36 pages, 2 figures, accepted for publication in Phys. Rev.
Long-range behavior of the optical potential for the elastic scattering of charged composite particles
The asymptotic behavior of the optical potential, describing elastic
scattering of a charged particle off a bound state of two charged, or
one charged and one neutral, particles at small momentum transfer
or equivalently at large intercluster distance
, is investigated within the framework of the exact three-body
theory. For the three-charged-particle Green function that occurs in the exact
expression for the optical potential, a recently derived expression, which is
appropriate for the asymptotic region under consideration, is used. We find
that for arbitrary values of the energy parameter the non-static part of the
optical potential behaves for as
. From this we derive for the
Fourier transform of its on-shell restriction for the behavior , i.e.,
dipole or quadrupole terms do not occur in the coordinate-space asymptotics.
This result corroborates the standard one, which is obtained by perturbative
methods. The general, energy-dependent expression for the dynamic
polarisability is derived; on the energy shell it reduces to the
conventional polarisability which is independent of the energy. We
emphasize that the present derivation is {\em non-perturbative}, i.e., it does
not make use of adiabatic or similar approximations, and is valid for energies
{\em below as well as above the three-body dissociation threshold}.Comment: 35 pages, no figures, revte
The Z--> l^+ l^- and W--> nu_l l^+ decays in the noncommutative standard model}}
We study Z--> l^+ l^- and W--> nu_l l^+ decays in the standard model
including the noncommutative effects. We observe that these effects appear in
the flavor dependent part of the decay widths of the processes under
consideration and therefore, they are more effective for the heavy lepton
decays.Comment: 8 pages, 5 Figure
Lateral optical anisotropy of type-II interfaces in the tight-binding approach
We have developed the tight-binding theory to study electronic and optical
properties of type-II heterostructures CA/C'A' grown from the zinc-blende
semiconductors CA and C'A' along the crystallographic direction [001]. The
sp^3s* nearest-neighbor tight-binding model with allowance for the spin-orbit
interaction is used to calculate the energy states and the in-plane linear
polarization of the spatially-indirect band-edge photoluminescence of InAs/AlSb
and ZnSe/BeTe multi-layered structures. The interface parameters for a pair of
the nonstandard planes C-A' or C'-A are considered as fitting variables. A wide
range of these parameters are shown to allow Tamm-like hole states localized at
the interfaces. The theory leads to giant values of the light polarization in
the both type-II heterosystems in agreement with existing experimental
findings.Comment: 9 pages, 6 figures, submitted to Phys. Rev.
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