Two-loop three-gluon vertex in zero-momentum limit
  The two-loop three-gluon vertex is calculated in an arbitrary covariant gauge, in the limit when one of the external momenta vanishes. The differential Ward-Slavnov-Taylor (WST) identity related to this limit is discussed, and the relevant results for the ghost-gluon vertex and two-point functions are obtained. Together with the differential WST identity, they provide another independent way for calculating the three-gluon vertex. The renormalization of the results obtained is also presented. 
A. I. Davydychev (Bergen, Moscow), P. Osland (Bergen, DESY) and O. V.   Tarasov (DESY-Zeuthen)