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41.
We derive the set of inversion relations allowing to establish the link between the dual parametrization of GPDs and a broad
class of phenomenological models for GPDs. As an example we consider the results of the calculation of the pion GPD in the
nonlocal chiral quark model (NlCQM) to recover the set of forward-like functions Q
2ν representing this GPD in the framework of dual parametrization. We also argue that the Abel tomography method overlooks possible
δ -function-like contributions to the GPD quintessence function which make explicit contribution to the D form factor. 相似文献
42.
M. Modarres M. M. Yazdanpanah F. Zolfagharpour 《The European Physical Journal A - Hadrons and Nuclei》2007,32(3):327-333
The electromagnetic polarizabilities of the nucleon are shown to be essentially composed of the nonresonant α
p(E
0+) = + 3.2, α
n(E
0+) = + 4.1, the t-channel α
t
p, n = - β
t
p, n = + 7.6 and the resonant β
p, n(P
33(1232)) = + 8.3 contributions (in units of 10-4fm^3). The remaining deviations from the experimental data Δα
p = 1.2±0.6, Δβ
p = 1.2±0.6, Δα
n = 0.8±1.7 and Δβ
n = 2.0±1.8 are contributed by a larger number of resonant and nonresonant processes with cancellations between the contributions.
This result confirms that dominant contributions to the electric and magnetic polarizabilities may be represented in terms
of two-photon coupling to the σ-meson having the predicted mass m
σ
= 666MeV and two-photon width Γ
γγ
= 2.6keV. 相似文献
43.
The collective resonant photoresponse in Si/SiGe structures with a 2DEG under microwave radiation is reported for the first time. The application of microwave radiation of various frequencies results in resonant photoconductivity at magnetic field values that are systematically lower than expected for the cyclotron resonance (CR) in an infinitely large two-dimensional electron system. The analysis of the data shows that the observed microwave radiation induced response is dominated by plasmon excitations. 相似文献
44.
Non-linear elastic wave spectroscopy (NEWS) has been shown to exhibit a high degree of sensitivity to both distributed and isolated non-linear scatterers in solids. In the case of an isolated non-linear scatterer such as a crack, by combining the elastic energy localization of time reversal (TR) with NEWS, it is shown that one can isolate non-linear scatterers in solids. The experiments reviewed here present two distinct methods of combining TR and NEWS for this purpose. The techniques each have there own advantages and disadvantages, with respect to each other and other non-linear methods, which are discussed. 相似文献
45.
The concepts of Wigner time delay and Wigner–Smith matrix allow us to characterise temporal aspects of a quantum scattering process. The paper reviews the statistical properties of the Wigner time delay for disordered systems; the case of disorder in 1D with a chiral symmetry is discussed and the relation with exponential functionals of the Brownian motion is underlined. Another approach for the analysis of time delay statistics is the random matrix approach, from which we review few results. As a practical illustration, we briefly outline a theory of non-linear transport and AC transport developed by Büttiker and coworkers, where the concept of Wigner–Smith time delay matrix is a central piece allowing us to describe screening properties in out-of-equilibrium coherent conductors. 相似文献
46.
47.
48.
I.V. Anikin D. Binosi R. Medrano S. Noguera V. Vento 《The European Physical Journal A - Hadrons and Nuclei》2002,14(1):95-103
The study of deeply virtual Compton scattering (DVCS) has shown that electromagnetic gauge invariance requires, to leading
order, not only twist-two but additional twist-three contributions. We apply this analysis and, using the Ellis-Furmanski-Petronzio
factorization scheme, compute the single- (electron) spin asymmetry arising in the collision of longitudinally polarized electrons
with hadrons up to twist-3 accuracy. In order to simplify the kinematics we restrict the actual calculation to pions in the
chiral limit. The process is described in terms of the generalized parton distribution functions which we obtain within a
bag model framework.
Received: 7 November 2001 / Accepted: 25 February 2002 相似文献
49.
Bloom-Gilman quark-hadron duality of nuclear spin structure function is studied by comparing the integral of g1 from perturbative QCD prediction in the scaling region to the moment of g1 in the resonance region. The spin structure function in the resonance region is estimated by the parametrization forms of non-resonance background and of resonance contributions. The uncertainties of our calculations due to those parametrization forms are discussed. Moreover, the effect of the (1232)-resonance in the first resonance region and the role of the resonances in the second resonance region are explicitly shown. Elastic peak contribution to the duality is also analyzed. 相似文献
50.
M. Kopytin 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):575-577
Measurements of azimuthal cross-section asymmetries from deeply virtual Compton scattering on transversely and longitudinally
polarized hydrogen and longitudinally polarized deuterium targets at HERMES are reported. By comparing the HERMES results
on the transverse target-spin asymmetry with theoretical calculations based on a phenomenological model of generalized parton
distributions, a model-dependent constraint on the total angular momentum carried by quarks in the nucleon is obtained. 相似文献