Higher Order QCD Corrections to $b\to c\overline{c}s$
  We calculate the ${\cal O}(\alpha_s^2 \beta_0 )$ corrections to the decay rate $b\rightarrow c\bar c s$. For reasonable values of $m_c/m_b$ this term is of the same order as both the one-loop and $\CO(\alpha_s^2 \log^2 m_W/m_b)$ corrections to the decay rate. For $m_c/m_b=0.3$ the $\CO(\alpha_s^2\beta_0)$ corrections enhance the rate by $\sim 18\%$ . We also discuss the $\CO(\alpha_s^2\beta_0)$ corrections to $R_\tau$, the $B$ semileptonic branching fraction and the charm multiplicity. 
Ming Lu, Michael Luke, Martin J. Savage, and Brian H. Smith