QCD corrections to charged Higgs-mediated $b \to c ����$ decay

We calculate the $O(��_s)$ corrections to the charged Higgs mediated inclusive semi-tauonic $B$ decay. By working in the Landau gauge, we demonstrate how to obtain the charged Higgs contributions (both direct and interference terms) from the known QCD corrections to $t \to b H^+$. Combining our results with $O(1/m_b^2)$ corrections to the spectator model and comparing the theoretical prediction with the recent experimental measurements, we find a model-independent $2��$ upper bound on the ratio of Higgs vacuum expectation values, $\tan��
10 pages, 1 figure, revtex