====== TTP05-03 Four-Loop Singlet Contribution to the $\rho$ Parameter ======
 
 
   <hidden TTP05-03  Four-Loop Singlet Contribution to the $\rho$ Parameter >   We compute the four-loop contribution to the electroweak $\rho$
   parameter induced by the singlet diagrams of the $Z$-boson
   self-energy. The numerical impact on the weak mixing angle and the
   $W$-boson mass is small.
 </hidden>
|**Y. Schr\"oder, M. Steinhauser**  | 
|**  Phys. Lett. B   622 124-130 2005  **  |
| {{preprints:2005:ttp05-03.pdf|PDF}} {{preprints:2005:ttp05-03.ps|PostScript}} [[http://arxiv.org/abs/hep-ph/0504055|arXiv]]   |
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