paper

Towards a fitting procedure for deeply virtual Compton scattering at next-to-leading order and beyond

arXiv:hep-ph/0703179 · doi:10.1016/j.nuclphysb.2007.10.029

Abstract

Combining dispersion and operator product expansion techniques, we derive the conformal partial wave decomposition of the virtual Compton scattering amplitude in terms of complex conformal spin to twist-two accuracy. The perturbation theory predictions for the deeply virtual Compton scattering (DVCS) amplitude are presented in next-to-leading order for both conformal and modified minimal subtraction scheme. Within a conformal subtraction scheme, where we exploit predictive power of conformal symmetry, the radiative corrections are presented up to next-to-next-to-leading order accuracy. Here, because of the trace anomaly, the mixing of conformal moments of generalized parton distributions (GPD) at the three-loop level remains unknown. Within a new proposed parameterization for GPDs, we then study the convergence of perturbation theory and demonstrate that our formalism is suitable for a fitting procedure of DVCS observables.

LaTeX, 100 pages, 16 figures, 5 tables; Secs. 5.1 and 5.2 revised, minor corrections, version to be published in Nucl.Phys.B

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