$1/m_b$ source in inclusive b-hadron decays
  We show that threshold resummation of the end-point logarithms in inclusive $b$-hadron decays leads to a Sudakov factor, which introduces $1/m_b$ power corrections through infrared renormalons. These power corrections are strong enough to account for the observed semileptonic branching ratio, charm yield, and lifetime ratios by breaking the local quark-hadron duality. 
Huei-Shih Liao and Hsiang-nan Li