Bosonic corrections to the effective leptonic weak mixing angle at the   two-loop level
  Details of the recent calculation of the two-loop bosonic corrections to the effective leptonic weak mixing angle are presented. In particular, the expansion in the difference of the W and Z boson masses is studied and some of the master integrals needed are given in analytic form. 
M. Czakon, M. Awramik, A. Freitas