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On the gauge invariance of the DVCS amplitude

I. V. Anikin·B. Pire·O. V. Teryaev
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Abstract

We analyze in detail the problem of gauge invariance of the deeply vitual Compton scattering (DVCS) amplitude. Using twist 3 one-gluon exchange diagram contributions and the QCD equations of motion, we derive the general gauge invariant expression of the DVCS amplitude on a (pseudo)scalar particle (pion, $He^4$). Similarly to the case of deep inelastic scattering, the amplitude does not depend on the twist-3 quark-gluon correlations at the Born level. The contribution of the derived amplitude to the single-spin asymmetry with longitudinally polarized lepton is calculated.

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I. V. Anikin, B. Pire, O. V. Teryaev. 2000-04-10. On the gauge invariance of the DVCS amplitude. https://doi.org/10.1103/physrevd.62.071501

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