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Title: Small-x nuclear shadowing from diffractive scattering

Abstract

We calculate nuclear shadowing ratios at small Bjorken-x for nuclei in the mass range 3<A<239 in the framework of a generalized form of the Gribov theory. The diffractive dissociation cross sections needed as inputs are taken from the FNAL (Fermi National Laboratory) and HERA (Hadron-Electron Ring Accelerator) experiments. Our calculations cover a wide range of energies between 12.8 and 231 GeV. The effects of the inclusion of subleading Reggeons on nuclear shadowing are investigated. At lower energies our results are compared to available data from the New Muon Collaboration (NMC) and E665 Collaboration (E665) experiments at x{approx_equal}10{sup -4}. At higher energies subleading Reggeons are found to contribute significantly to nuclear shadowing.

Authors:
;  [1]
  1. Center for Nuclear Research, Department of Physics, Kent State University, Kent, Ohio 44242 (United States)
Publication Date:
OSTI Identifier:
20995315
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. C, Nuclear Physics; Journal Volume: 75; Journal Issue: 5; Other Information: DOI: 10.1103/PhysRevC.75.054911; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; CROSS SECTIONS; ELECTRON-RING ACCELERATORS; GEV RANGE; HADRONS; MULTIPERIPHERAL MODEL; MUONS; PARTICLE PRODUCTION; SCATTERING

Citation Formats

Adeluyi, A., and Nguyen, T.. Small-x nuclear shadowing from diffractive scattering. United States: N. p., 2007. Web. doi:10.1103/PHYSREVC.75.054911.
Adeluyi, A., & Nguyen, T.. Small-x nuclear shadowing from diffractive scattering. United States. doi:10.1103/PHYSREVC.75.054911.
Adeluyi, A., and Nguyen, T.. Tue . "Small-x nuclear shadowing from diffractive scattering". United States. doi:10.1103/PHYSREVC.75.054911.
@article{osti_20995315,
title = {Small-x nuclear shadowing from diffractive scattering},
author = {Adeluyi, A. and Nguyen, T.},
abstractNote = {We calculate nuclear shadowing ratios at small Bjorken-x for nuclei in the mass range 3<A<239 in the framework of a generalized form of the Gribov theory. The diffractive dissociation cross sections needed as inputs are taken from the FNAL (Fermi National Laboratory) and HERA (Hadron-Electron Ring Accelerator) experiments. Our calculations cover a wide range of energies between 12.8 and 231 GeV. The effects of the inclusion of subleading Reggeons on nuclear shadowing are investigated. At lower energies our results are compared to available data from the New Muon Collaboration (NMC) and E665 Collaboration (E665) experiments at x{approx_equal}10{sup -4}. At higher energies subleading Reggeons are found to contribute significantly to nuclear shadowing.},
doi = {10.1103/PHYSREVC.75.054911},
journal = {Physical Review. C, Nuclear Physics},
number = 5,
volume = 75,
place = {United States},
year = {Tue May 15 00:00:00 EDT 2007},
month = {Tue May 15 00:00:00 EDT 2007}
}
  • We calculate the nuclear shadowing ratio for a wide range of nuclei at small Bjorken-x in the framework of Gribov theory. The coherent contribution to the (virtual) photon-nucleon cross section is obtained in terms of the diffractive dissociation cross section. Information on diffraction from FNAL and HERA is used. Our results are compared to available data from the New Muon Collaboration and E665 Collaboration experiments at x{approx_equal}10{sup -4}.
  • We generalize the leading twist theory of nuclear shadowing and calculate quark and gluon generalized parton distributions (GPDs) of spinless nuclei. We predict very large nuclear shadowing for nuclear GPDs. In the limit of the purely transverse momentum transfer, our nuclear GPDs become impact-parameter-dependent nuclear parton distribution functions (PDFs). Nuclear shadowing induces nontrivial correlations between the impact parameter b and the light-cone fraction x. We make predictions for the deeply virtual Compton scattering (DVCS) amplitude and the DVCS cross section on {sup 208}Pb at high energies. We calculate the cross section of the Bethe-Heitler (BH) process and address the issuemore » of the extraction of the DVCS signal from the eA{yields}e{gamma}A cross section. We find that the eA{yields}e{gamma}A differential cross section is dominated by DVCS at the momentum transfer t near the minima of the nuclear form factor. We also find that nuclear shadowing leads to dramatic oscillations of the DVCS beam-spin asymmetry, A{sub LU}, as a function of t. The position of the points where A{sub LU} changes sign is directly related to the magnitude of nuclear shadowing.« less
  • We generalize the leading twist theory of nuclear shadowing and calculate quark and gluon generalized parton distributions (GPDs) of spinless nuclei. We predict very large nuclear shadowing for nuclear GPDs. In the limit of the purely transverse momentum transfer, our nuclear GPDs become impact parameter dependent nuclear parton distributions (PDFs). Nuclear shadowing induces non-trivial correlations between the impact parametermore » $b$ and the light-cone fraction $x$. We make predictions for the deeply virtual Compton scattering (DVCS) amplitude and the DVCS cross section on $$^{208}$$Pb at high energies. We calculate the cross section of the Bethe-Heitler (BH) process and address the issue of the extraction of the DVCS signal from the $$e A \to e \gamma A$$ cross section. We find that the $$e A \to e \gamma A$$ differential cross section is dominated by DVCS at the momentum transfer $t$ near the minima of the nuclear form factor. We also find that nuclear shadowing leads« less
  • A hybrid moment-method/geometrical-theory-of-diffraction technique (MM/GTD) has been implemented to numerically calculate the electromagnetic scattering from one-dimensionally rough surfaces at extreme illumination angles (down to 0{degree} grazing). The hybrid approach allows the extension of the modeled scattering surface to infinity, avoiding the artificial edge diffraction that prevents use of the standard moment method at the smallest grazing angles. Numerical calculation of the backscattering from slightly rough large-scale surfaces approximating ocean wave features shows that roughness in strongly shadowed regions can contribute significantly to the total backscatter at vertical polarization. This is observed when the shadowing obstacle is several wavelengths high, andmore » the magnitude of the shadow-region contribution does not depend on the radius-of-curvature of the shadowing feature. Strongly shadowed roughness does not significantly contribute to the backscatter at horizontal polarization, although weakly shadowed roughness near the incidence shadow boundary does. The calculations indicate that a shadowing-corrected two-scale model may be able to predict the distributed-surface portion of the sea-surface scattering from the ocean surface at grazing angles down to about 15{degree}, but at lower grazing the shadowing and large-scale curvature of the surface prevent the establishment of a Bragg resonance and invalidate the model.« less
  • The close connection between the quantum phase space Wigner distribution of small-x gluons and the color dipole scattering amplitude is investigated, and studying it experimentally is proposed in the hard diffractive dijet production at the planned electron-ion collider. The angular correlation between the nucleon recoiled momentum and the dijet transverse momentum probes the nontrivial correlation in the phase space Wigner distribution. This experimental study not only provides three-dimensional tomographic pictures of gluons inside high energy protons - it gives a unique and interesting signal for the small-x dynamics with QCD evolution effects.