====== TTP00-08 The three-loop on-shell renormalization of QCD and QED ======
 
 
   <hidden TTP00-08  The three-loop on-shell renormalization of QCD and QED >   We describe a calculation of the on-shell renormalization factors in QCD 
   and QED at the three loop level. Explicit results for the fermion mass 
   renormalization factor Zm and the on-shell fermion wave function 
   renormalization constant Z2 are given. We find that at O(alpha_s^3) the
   wave function renormalization constant Z2 in QCD becomes gauge dependent 
   also in the on-shell scheme, thereby disproving the ``gauge-independence'' 
   conjecture based on an earlier two-loop result. As a byproduct, we derive 
   an O(alpha_s^3) contribution to the anomalous dimension of the heavy quark 
   field in HQET. 
 </hidden>
|**Kirill Melnikov and Timo van Ritbergen**  | 
|**  Nucl. Phys.  B591 515-546 2000  **  |
| {{preprints:2000:ttp00-08.pdf|PDF}} {{preprints:2000:ttp00-08.ps|PostScript}} [[http://arxiv.org/abs/hep-ph/0005131|arXiv]]   |
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