247 research outputs found
Comment on Mott Scattering in strong Laser Field
The first differential cross section for Mott scattering of a Dirac-Volkov
electron is reviewed. The expression (26) derived by Szymanowski et al.
[Physical Review A {\bf 56}, 3846,(1997)] is corrected. In particular, we
disagree with the expression of they obtained and
we give the exact coefficients multiplying the various Bessel functions
appearing in the scattering differential cross section.Comment: 16 pages, LaTex, added reference for section 3, corrected some
typosReport no: LPHEA 02-0
Noise and deviation effects in a bichromatic Raman white light cavity
We analyze the effects of noise and parameter deviations in a bichromatic
Raman type white light cavity, with potential applications in precision
measurements such as gravitational wave detection. The results show that the
dispersion variation induced by parameter deviation can be controlled within
. The laser phase noise decreases the dispersion magnitude while the
amplitude noise increases it. Although we can always adjust the parameters to
satisfy the white light condition, both noises make the cavity transmission
curve uneven.Comment: 5 pages, 3 figure
On AdS/QCD correspondence and the partonic picture of deep inelastic scattering
We critically examine the question of scaling of the Deep Inelastic
Scattering process in the medium Bjorken x region on a scalar boson in the
framework of the AdS/QCD correspondence. To get the right polarization
structure of the forward electroproduction amplitude, we show that one needs to
add (at least) the scalar to scalar and scalar to vector hadronic amplitudes.
This illustrates how the partonic picture may emerge from a simple scenario
based on the AdS/QCD correspondence, provided one allows the conformal
dimension of the hadronic field to equal 1 and use the concept of "hadron -
parton duality" .Comment: Second version with a few added clarifications and references. Third
version with a misprint corrected in Eq. 35 and following unnumbered
equation; to appear in Physics Letters
Spin dynamics in the Kapitza-Dirac effect
Electron spin dynamics in Kapitza-Dirac scattering from a standing laser wave
of high frequency and high intensity is studied. We develop a fully
relativistic quantum theory of the electron motion based on the time-dependent
Dirac equation. Distinct spin dynamics, with Rabi oscillations and complete
spin-flip transitions, is demonstrated for Kapitza-Dirac scattering involving
three photons in a parameter regime accessible to future high-power X-ray laser
sources. The Rabi frequency and, thus, the diffraction pattern is shown to
depend crucially on the spin degree of freedom
Relativistic and retardation effects in the two--photon ionization of hydrogen--like ions
The non-resonant two-photon ionization of hydrogen-like ions is studied in
second-order perturbation theory, based on the Dirac equation. To carry out the
summation over the complete Coulomb spectrum, a Green function approach has
been applied to the computation of the ionization cross sections. Exact
second-order relativistic cross sections are compared with data as obtained
from a relativistic long-wavelength approximation as well as from the scaling
of non-relativistic results. For high-Z ions, the relativistic wavefunction
contraction may lower the two-photon ionization cross sections by a factor of
two or more, while retardation effects appear less pronounced but still give
rise to non-negligible contributions.Comment: 6 pages, 2 figure
Heavy quark production as sensitive test for an improved description of high energy hadron collisions
QCD dynamics at small quark and gluon momentum fractions or large total
energy, which plays a major role for HERA, the Tevatron, RHIC and LHC physics,
is still poorly understood. For one of the simplest processes, namely
bottom-antibottom production, next-to-leading-order perturbation theory fails.
We show that the combination of two recently developed theoretical concepts,
the k_perp-factorization and the next-to-leading-logarithmic-approximation BFKL
vertex, gives perfect agreement with data. One can therefore hope that these
concepts provide a valuable foundation for the description of other high energy
processes.Comment: RevTeX, 4 pages, 7 figures titel and abstract changed, several
formulations modified in the text, 1 figure droppe
Polarization of the electron and positron produced in combined Coulomb and strong laser fields
The process of production in the superposition of a Coulomb and a
strong laser field is considered. The pair production rate integrated over the
momentum and summed over the spin projections of one of the particles is
derived exactly in the parameters of the laser field and in the Born
approximation with respect to the Coulomb field. The case of a monochromatic
circularly polarized laser field is considered in detail. A very compact
analytical expression of the pair production rate and its dependence on the
polarization of one of the created particles is obtained in the quasiclassical
approximation for the experimentally relevant case of an undercritical laser
field. As a result, the polarization of the created electron (positron) is
derived.Comment: 16 pages, no figure
Vector meson electroproduction at next-to-leading order
The process of a light neutral vector meson electroproduction is studied in
the framework of QCD factorization in which the amplitude factorizes in a
convolution of the nonperturbative meson distribution amplitude and the
generalized parton densities with the perturbatively calculable hard-scattering
amplitudes. We derive a complete set of hard-scattering amplitudes at
next-to-leading order for the production of vector mesons, .Comment: latex, 6 pages, with corrected Eq. (12) and added remark on
dimensional regularisatio
Effective Action for High-Energy Scattering in Gravity
The multi-Regge effective action is derived directly from the linearized
gravity action. After excluding the redundant field components we separate the
fields into momentum modes and integrate over modes which correspond neither to
the kinematics of scattering nor to the one of exchanged particles. The
effective vertices of scattering and of particle production are obtained as
sums of the contributions from the triple and quartic interaction terms and the
fields in the effective action are defined in terms of the two physical
components of the metric fluctuation.Comment: 15 pages, LATE
Role of electromagnetically induced transparency in resonant four-wave-mixing schemes.
Published versio
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