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Title: Deeply virtual Compton scattering from gauge/gravity duality

Abstract

We use gauge/gravity duality to study deeply virtual Compton scattering (DVCS) in the limit of high center of mass energy at fixed momentum transfer, corresponding to the limit of low Bjorken x, where the process is dominated by the exchange of the pomeron. At strong coupling, the pomeron is described as the graviton Regge trajectory in AdS space, with a hard wall to mimic confinement effects. This model agrees with HERA data in a large kinematical range. The behavior of the DVCS cross section for very high energies, inside saturation, can be explained by a simple AdS black disk model. In a restricted kinematical window, this model agrees with HERA data as well.

Authors:
;  [1]
  1. University of Porto (Portugal)
Publication Date:
OSTI Identifier:
22116940
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1523; Journal Issue: 1; Conference: DIFFRACTION 2012: International workshop on diffraction in high energy physics, Lanzarote, Canary Islands (Spain), 10-15 Sep 2012; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ANTI DE SITTER SPACE; COMPTON EFFECT; CROSS SECTIONS; DUALITY; GAUGE INVARIANCE; GRAVITATION; GRAVITONS; HERA STORAGE RING; MOMENTUM TRANSFER; MULTIPARTICLE SPECTROMETERS; PARTICLE IDENTIFICATION; PARTICLE KINEMATICS; POMERANCHUK PARTICLES; QUANTUM FIELD THEORY; REGGE TRAJECTORIES; SPACE-TIME

Citation Formats

Costa, Miguel S., and Djuric, Marko. Deeply virtual Compton scattering from gauge/gravity duality. United States: N. p., 2013. Web. doi:10.1063/1.4802124.
Costa, Miguel S., & Djuric, Marko. Deeply virtual Compton scattering from gauge/gravity duality. United States. doi:10.1063/1.4802124.
Costa, Miguel S., and Djuric, Marko. 2013. "Deeply virtual Compton scattering from gauge/gravity duality". United States. doi:10.1063/1.4802124.
@article{osti_22116940,
title = {Deeply virtual Compton scattering from gauge/gravity duality},
author = {Costa, Miguel S. and Djuric, Marko},
abstractNote = {We use gauge/gravity duality to study deeply virtual Compton scattering (DVCS) in the limit of high center of mass energy at fixed momentum transfer, corresponding to the limit of low Bjorken x, where the process is dominated by the exchange of the pomeron. At strong coupling, the pomeron is described as the graviton Regge trajectory in AdS space, with a hard wall to mimic confinement effects. This model agrees with HERA data in a large kinematical range. The behavior of the DVCS cross section for very high energies, inside saturation, can be explained by a simple AdS black disk model. In a restricted kinematical window, this model agrees with HERA data as well.},
doi = {10.1063/1.4802124},
journal = {AIP Conference Proceedings},
number = 1,
volume = 1523,
place = {United States},
year = 2013,
month = 4
}
  • In the framework of generalized parton distributions, we study the helicity-dependent and independent cross sections measured in Hall A and the beam spin asymmetries measured in Hall B at Jefferson Laboratory. We perform a global fit of these data and fits on each kinematic bin. We extract the real and imaginary parts of the Compton form factor H under the main hypothesis of dominance of the generalized parton distribution H and twist 2 accuracy. We discuss our results and compare to previous extractions as well as to the VGG model. We pay extra attention to the estimation of errors onmore » the extraction of H.« less
  • The Fourier transform of the deeply virtual Compton scattering amplitude (DVCS) with respect to the skewness parameter {zeta} = Q{sup 2}/2p {center_dot} q can be used to provide an image of the target hadron in the boost-invariant variable {sigma}, the coordinate conjugate to light-front time {tau} = t + z/c. As an illustration, we construct a consistent covariant model of the DVCS amplitude and its associated generalized parton distributions using the quantum fluctuations of a fermion state at one loop in QED, thus providing a representation of the light-front wavefunctions of a lepton in {sigma} space. A consistent model formore » hadronic amplitudes can then be obtained by differentiating the light-front wavefunctions with respect to the bound-state mass. The resulting DVCS helicity amplitudes are evaluated as a function of {sigma} and the impact parameter {rvec b}{sub {perpendicular}}, thus providing a light-front ''photograph'' of the target hadron in a frame-independent three-dimensional light-front coordinate space. We find that in the models studied, the Fourier transform of the DVCS amplitudes exhibit diffraction patterns. The results are analogous to the diffractive scattering of a wave in optics where the distribution in {sigma} measures the physical size of the scattering center in a one-dimensional system.« less
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  • The Fourier transform of the deeply virtual Compton scattering amplitude (DVCS) with respect to the skewness parameter {zeta}=Q{sup 2}/2p{center_dot}q can be used to provide an image of the target hadron in the boost-invariant variable {sigma}, the coordinate conjugate to light-front time {tau}=t+z/c. As an illustration, we construct a consistent covariant model of the DVCS amplitude and its associated generalized parton distributions using the quantum fluctuations of a fermion state at one loop in QED, thus providing a representation of the light-front wave functions (LFWFs) of a lepton in {sigma} space. A consistent model for hadronic amplitudes can then be obtainedmore » by differentiating the light-front wave functions with respect to the bound-state mass. The resulting DVCS helicity amplitudes are evaluated as a function of {sigma} and the impact parameter b-vector{sub perpendicular}, thus providing a light-front image of the target hadron in a frame-independent three-dimensional light-front coordinate space. Models for the LFWFs of hadrons in (3+1) dimensions displaying confinement at large distances and conformal symmetry at short distances have been obtained using the AdS/CFT method. We also compute the LFWFs in this model in invariant three-dimensional coordinate space. We find that, in the models studied, the Fourier transform of the DVCS amplitudes exhibit diffraction patterns. The results are analogous to the diffractive scattering of a wave in optics where the distribution in {sigma} measures the physical size of the scattering center in a one-dimensional system.« less