Inclusive Semi-leptonic B Decays to order 1/m_b^4
  We give a systematic way to compute higher orders in the 1/m_b expansion in inclusive semi-leptonic decays at tree level. We reproduce the known 1/m_b^3 terms and compute the 1/m_b^4 terms at tree level. The appearing non-perturbative parameters and the impact on the determination of V_{cb} are discussed. 
Benjamin M. Dassinger, Thomas Mannel, Sascha Turczyk (Univ. Siegen)