====== TTP98-04 Singlet Polarization Functions at O(\alpha_s^2) ======
 
 
   <hidden TTP98-04  Singlet Polarization Functions at O(\alpha_s^2) > We consider the three-loop singlet diagrams induced by axial-vector,
 scalar and pseudo-scalar currents.  Expansions for small and large
 external momentum $q$ are presented.  They are used in combination
 with conformal mapping and Pad\'e approximations in order to arrive at
 results for the polarization functions valid for all $q^2$. Results are
 presented for the imaginary parts which are directly related to physical
 quantities like the production of top quarks or the decay of scalar or
 pseudo-scalar Higgs bosons.
 </hidden>
|**K.G. Chetyrkin, R. Harlander and M. Steinhauser**  | 
|** Phys. Rev. D 58 014012 1998  **  |
| {{preprints:1998:ttp98-04.pdf|PDF}} {{preprints:1998:ttp98-04.ps|PostScript}} [[http://arxiv.org/abs/hep-ph/9801432|arXiv]]   |
| |