T. Altinoluk, B. Pire, L. Szymanowski, S. Wallon
We calculate the quark coefficient function Tq(x,xi) that enters the factorized amplitude for deeply virtual Compton scattering (DVCS) at all order in a soft and collinear gluon approximation, focusing on the leading double logarithmic behavior in x +/- xi, where x +/- xi is the light cone momentum fraction of the incoming/outgoing quarks. We show that the dominant part of the known one loop result can be understood in an axial gauge as the result of a semi-eikonal approximation to the box diagram. We then derive an all order result for the leading contribution of the ladder diagrams and deduce a resummation formula valid in the vicinity of the boundaries of the regions defining the energy flows of the incoming/outcoming quarks, i.e. x = +/- xi. The resummed series results in a simple closed expression.
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http://arxiv.org/abs/1207.4609
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