Local two-photon couplings and the J=0 fixed pole in real and virtual Compton scattering



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Llanes Estrada, Felipe José and Brodsky, Stanley J and Szczepaniak, Adam P (2009) Local two-photon couplings and the J=0 fixed pole in real and virtual Compton scattering. Physical Review D , 79 (3). ISSN 1550-7998

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Official URL: http://dx.doi.org/10.1103/PhysRevD.79.033012


The local coupling of two photons to the fundamental quark currents of a hadron gives an energy-independent contribution to the Compton amplitude proportional to the charge squared of the struck quark, a contribution which has no analog in hadron scattering reactions. We show that this local contribution has a real phase and is universal, giving the same contribution for real or virtual Compton scattering for any photon virtuality and skewness at fixed momentum transfer squared t. The t dependence of this J=0 fixed Regge pole is parameterized by a yet unmeasured even charge conjugation form factor of the target nucleon. The t=0 limit gives an important constraint on the dependence of the nucleon mass on the quark mass through the Weisberger relation. We discuss how this 1/x form factor can be extracted from high-energy deeply virtual Compton scattering and examine predictions given by models of the H generalized parton distribution.

Item Type:Article
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© 2009 The American Physical Society.

Uncontrolled Keywords:Generalized Parton Distributions, Hard Exclusive Processes, Large-Momentum-Transfer, Form- Actors, Quantum Chromodynamics, Proton-Antiproton, Pair Production, Model, Qcd, Phenomenology
Subjects:Sciences > Physics
ID Code:22788
Deposited On:17 Sep 2013 16:29
Last Modified:30 Jan 2018 08:02

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