M.G.Ryskin (PNPI)


Perturbative QCD at low scales: the role of infrared region


At the NLO level dimensional regularization sometimes produces a non-zero result of the \epsilon/\epsilon structure coming from the infrared region. We argue that the proper procedire is to first subtract from the NLO matrix element the contribution already generated at the same order of \alpha_s by the LO DGLAP splitting function convoluted with the LO matrix element. This prescription eleiminates the logarithmic infrared divergence, giving a well-defined result. However this result is different from that obtained within the conventional MS-bar scheme.