====== TTP97-05 Two-loop QCD corrections to semileptonic b decays at maximal recoil ======
 
 
   <hidden TTP97-05  Two-loop QCD corrections to semileptonic b decays at maximal recoil > We present a complete ${\cal O}(\alpha_s^2)$ correction to the
 differential width of the inclusive semileptonic decay $b\to cl\nu_l$
 at the kinematical point of vanishing invariant mass of the leptons,
 $q^2=0$.  Together with the recently computed ${\cal O}(\alpha_s^2)$
 correction at the upper boundary of the lepton invariant mass
 spectrum, this new information permits an estimate of the ${\cal
 O}(\alpha_s^2)$ effect in the total inclusive semileptonic decay width
 $b\to cl\nu_l$. We argue that the non-BLM part of the ${\cal
 O}(\alpha_s^2)$ correction gives at most $1\%$ correction to the
 inclusive semileptonic decay width $b\to cl\nu_l$. This significantly
 improves the credibility of extracting $|V_{cb}|$ from the inclusive
 semileptonic decays of the $b$-hadrons.
 
 </hidden>
|**Andrzej Czarnecki and Kirill Melnikov**  | 
|** Phys. Rev. Lett. 78 3630 1997  **  |
| {{preprints:1997:ttp97-05.pdf|PDF}} {{preprints:1997:ttp97-05.ps|PostScript}} [[http://arxiv.org/abs/hep-ph/9703291|arXiv]]   |
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