Moments of heavy-light current correlators up to three loops
  We consider moments of the non-diagonal vector, axial-vector, scalar and pseudo-scalar current correlators involving two different massive quark flavours up to three-loop accuracy. Expansions around the limits where one mass is zero and the equal-mass case are computed. These results are used to construct approximations valid for arbitrary mass values. 
Jens Hoff and Matthias Steinhauser
hep-ph