====== TTP99-38 Second Order Corrections to the Muon Lifetime and the Semileptonic $B$ Decay ======
 
 
   <hidden TTP99-38  Second Order Corrections to the Muon Lifetime and the Semileptonic $B$ Decay > In this article two-loop QED corrections to the muon decay and corrections of 
 order $\alpha_s^2$ to the semileptonic decay of the bottom quark are 
 considered. We compute the imaginary part of the four-loop diagrams 
 contributing to the corresponding fermion propagator in the limit of small 
 external momentum. The on-shell condition is obtained with the help of a 
 conformal mapping and Pad\'e approximation. Via this method we confirm the 
 existing results by an independent calculation.
 </hidden>
|**M. Steinhauser and T. Seidensticker**  | 
|**  Physics Letters   B 467 271-278 1999  **  |
| {{preprints:1999:ttp99-38.pdf|PDF}} {{preprints:1999:ttp99-38.ps|PostScript}} [[http://arxiv.org/abs/hep-ph/9909436|arXiv]]   |
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