Double logarithms resummation in exclusive processes : the surprising behavior of DVCS
arXiv:1309.2508
Abstract
Double logarithms resummation has been much studied in inclusive as well as exclusive processes. The Sudakov mechanism has often be the crucial tool to exponentiate potentially large contributions to amplitudes or cross-sections near phase-space boundaries. We report on a recent work where a very different pattern emerges : the DVCS quark coefficient function C(x,ξ) develops, near the particular point x=ξ, a non-alternate series in α_s^n log^{2n}(x-ξ) which may be resummed in a cosh[K sqrt α_s log(x-ξ)] factor. This result is at odds with the known result for the corresponding coefficient function for the pion transition form factor near the end point C(z) although they are much related through a z -> x/ξcorrespondence.
9 pages, 1 figure, Presented at the Low x workshop, May 30 - June 4 2013, Rehovot and Eilat, Israel