Three loop cusp anomalous dimension in QCD.
We present the full analytic result for the three loop angle-dependent cusp anomalous dimension in QCD. With this result, infrared divergences of planar scattering processes with massive particles can be predicted to that order. Moreover, we define a closely related quantity in terms of an effective coupling defined by the lightlike cusp anomalous dimension. We find evidence that this quantity is universal for any gauge theory and use this observation to predict the nonplanar n(f)-dependent terms of the four loop cusp anomalous dimension.
Budker Institute of Nuclear Physics SB RAS, Novosibirsk 630090, Russia and Novosibirsk State University, Novosibirsk 630090, Russia.
Andrey
A
Grozin
Institute for Advanced Study, Princeton, New Jersy 08540, USA.
Johannes M
JM
Henn
Institut de Physique Théorique, CEA Saclay, 91191 Gif-sur-Yvette Cedex, France.
Gregory P
GP
Korchemsky
Deutsches Elektronen-Synchrotron, DESY, Platanenallee 6, D15738 Zeuthen, Germany.
Peter
P
Marquard