A next-to-leading order QCD analysis of deeply virtual Compton scattering amplitudes

Abstract

We present a next-to-leading order (NLO) QCD analysis of unpolarized and polarized deeply virtual Compton scattering (DVCS) amplitudes, for two different input scenarios, in the $\bar{MS}$ scheme. We illustrate and discuss the size of the NLO effects and the behavior of the amplitudes in skewedness, $ζ$, and photon virtuality, $Q^2$. In the unpolarized case, at fixed $Q^2$, we find a remarkable effective power-law behaviour in $ζ$, akin to Regge factorization, over several orders of magnitude in $ζ$. We also quantify the ratio of real to imaginary parts of the DVCS amplitudes and their sensitivity to changes of the factorization scale.

12 pages, 12 figures, revtex, final version to be published in Phys. Rev. D. Corrected error in MRSA' distribution and modified extraplation behavior of GRSV00 distribution. Corrected error in +iεtreatment. Taking now correct sheaf of log. Errors in subtraction equations corrected. Figures and results for affected imaginary part of NLO amplitude changed accordingly