412 research outputs found
Large Logarithms in the Beam Normal Spin Asymmetry of Elastic Electron--Proton Scattering
We study a parity-conserving single-spin beam asymmetry of elastic
electron-proton scattering induced by an absorptive part of the two-photon
exchange amplitude. It is demonstrated that excitation of inelastic hadronic
intermediate states by the consecutive exchange of two photons leads to
logarithmic and double-logarithmic enhancement due to contributions of hard
collinear quasi-real photons. The asymmetry at small electron scattering angles
is expressed in terms of the total photoproduction cross section on the proton,
and is predicted to reach the magnitude of 20-30 parts per million. At these
conditions and fixed 4-momentum transfers, the asymmetry is rising
logarithmically with increasing electron beam energy, following the high-energy
diffractive behavior of total photoproduction cross section on the proton.Comment: 10 pages, 6 figures; typos fixed, a reference adde
Transverse target spin asymmetry in inclusive DIS with two-photon exchange
We study the transverse target spin dependence of the cross section for
inclusive electron-nucleon scattering with unpolarized beam. Such dependence is
absent in the one-photon exchange approximation (Christ-Lee theorem) and arises
only in higher orders of the QED expansion, from the interference of one-photon
and absorptive two-photon exchange amplitudes as well as from real photon
emission (bremsstrahlung). We demonstrate that the transverse spin-dependent
two-photon exchange cross section is free of QED infrared and collinear
divergences. We argue that in DIS kinematics the transverse spin dependence
should be governed by a "parton-like" mechanism in which the two-photon
exchange couples mainly to a single quark. We calculate the normal spin
asymmetry in an approximation where the dominant contribution arises from quark
helicity flip due to interactions with non-perturbative vacuum fields
(constituent quark picture) and is proportional to the quark transversity
distribution in the nucleon. Such helicity-flip processes are not significantly
Sudakov-suppressed if the infrared scale for gluon emission in the photon-quark
subprocess is of the order of the chiral symmetry breaking scale, mu_chiral^2
>> Lambda_QCD^2. We estimate the asymmetry in the kinematics of the planned
Jefferson Lab Hall A experiment to be of the order 10^{-4}, with different sign
for proton and neutron. We also comment on the spin dependence in the limit of
soft high-energy scattering.Comment: 22 pages, 14 figures; uses revtex
QED Radiative Corrections in Processes of Exclusive Pion Electroproduction
Formalism for radiative correction (RC) calculation in exclusive pion
electroproduction on the proton is presented. A FORTRAN code EXCLURAD is
developed for the RC procedure. The numerical analysis is done in the
kinematics of current Jefferson Lab experiments.Comment: 13 pages, 9 figures; requires RevTeX
Beam Single-Spin Asymmetry in Semi-Inclusive Deep Inelastic Scattering
We calculate, in a model, the beam spin asymmetry in semi-inclusive jet
production in deep inelastic scattering. This twist-3, -odd observable is
non-zero due to final state strong interactions. With reasonable choices for
the parameters, one finds an asymmetry of several percent, about the size seen
experimentally. We present the result both as an explicit asymmetry calculation
and as a model calculation of the new transverse-momentum dependent
distribution function .Comment: 10 pages, 6 figures; minor changes made in the discussion; version
accepted for publicatio
Scaling and Duality in Semi-exclusive Processes
We discuss extending scaling and duality studies to semi-exclusive processes.
We show that semi-exclusive hard pion photoproduction should exhibit scaling
behavior in kinematic regions where the photon and pion both interact directly
with the same quark. We show that such kinematic regions exist. We also show
that the constancy with changing momentum transfer of the resonance
peak/scaling curve ratio, familiar for many resonances in deep inelastic
scattering, is also expected in the semi-exclusive case.Comment: 8 pages, 4 figures, submitted to Phys.Rev.
Radiative Correction to the Transferred Polarization in Elastic Electron-Proton Scattering
Model independent radiative correction to the recoil proton polarization for
the elastic electron-proton scattering is calculated within method of electron
structure functions. The explicit expressions for the recoil proton
polarization are represented as a contraction of the electron structure and the
hard part of the polarization dependent contribution into cross-section. The
calculation of the hard part with first order radiative correction is
performed. The obtained representation includes the leading radiative
corrections in all orders of perturbation theory and the main part of the
second order next-to-leading ones. Numerical calculations illustrate our
analytical results.Comment: 14 pages, 4 figure
Integration of corporate technological foresight into the technological development management system in companies of oil and gas sector
The experience of leading multinational players in conducting corporate technological foresight shows that the key to its successful implementation is effective integration with the existing corporate strategic planning system.The issue of identifying the most important and necessary measures for integrating foresight into the corporate governance system of oil and gas companies has been considered in the article. The elements of the corporate management system with which it is necessary to build interrelation and description of options for strategies, have been presented, recommendations for conducting foresight for each of them have been given. It has been noted, that the use of foresight research has a significant impact on the effectiveness of individual projects and on the efficiency of companies' activity as a whole.The results obtained have showed that the effectiveness of the results of foresight directly depends on the company’s readiness to conduct it and the level of maturity of scientific and technical processes of innovative development of the company. The directions of the company’s management system, that have a particularly strong impact on the effectiveness of the results of foresight research have been highlighted, as well as methods for assessing the company’s readiness to conduct foresight have been proposed. An assessment of the options for applying foresight research depending on the company’s chosen model of innovative development and innovative development program has been given. It has been noted, that the greatest effect is achieved with a proactive management model that allows you to fully use the tools of foresight research, resulting forecasts. Using foresight for active and passive models doesn't give any advantages for the company, it leads to additional costs. The relationship between foresight and the most common organizational management structures, currently used in Russian oil and gas companies, has been shown
Theory and Applications of X-ray Standing Waves in Real Crystals
Theoretical aspects of x-ray standing wave method for investigation of the
real structure of crystals are considered in this review paper. Starting from
the general approach of the secondary radiation yield from deformed crystals
this theory is applied to different concreat cases. Various models of deformed
crystals like: bicrystal model, multilayer model, crystals with extended
deformation field are considered in detailes. Peculiarities of x-ray standing
wave behavior in different scattering geometries (Bragg, Laue) are analysed in
detailes. New possibilities to solve the phase problem with x-ray standing wave
method are discussed in the review. General theoretical approaches are
illustrated with a big number of experimental results.Comment: 101 pages, 43 figures, 3 table
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