====== TTP96-49 Penguin Zoology in $B\to\pi\pi$ and the Extraction of the CKM Angle $\alpha$ ======
 
 
   <hidden TTP96-49  Penguin Zoology in $B\to\pi\pi$ and the Extraction of the CKM Angle $\alpha$ > We reanalyze the decay $B_d\to\pi^+\pi^-$ without assuming dominance 
 of QCD penguins with internal top-quark exchanges. In that case the 
 weak phase of the $\bar b \to\bar d$ QCD penguin amplitude is not 
 related in a simple way to the CKM angle $\beta$. Nevertheless it is 
 still possible to extract the CKM angle $\alpha$ in a transparent and 
 almost model-independent way from the time-dependent CP-violating 
 asymmetry of the transition $B_d\to\pi^+\pi^-$. Aside from that
 CP asymmetry this approach needs as an input only amplitudes of decays 
 with branching ratios of order $10^{-5}$ and will thus be well within 
 reach at future $B$-factories.
 
 </hidden>
|**Robert Fleischer, Thomas Mannel**  | 
|** Phys. Lett. B397 269-274 1997  **  |
| {{preprints:1996:ttp96-49.pdf|PDF}} {{preprints:1996:ttp96-49.ps|PostScript}} [[http://arxiv.org/abs/hep-ph/9610357|arXiv]]   |
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