Inclusive Semitauonic $B$ Decays to Order ${\cal O} (Λ_{QCD}^3/m_b^3)$

Abstract

We calculate the decay width and the $τ$-lepton energy distribution as well as relevant moments for inclusive $\bar B \to X_c τ\bar ν_τ$ process including power corrections up to order $Λ_{QCD}^3/m_b^3$ and QCD corrections to the partonic level. We compare the result with the sum of the standard-model predictions of the branching fractions of the exclusive semileptonic $\bar B \to (D, D^*, D^{**}) τ\bar ν_τ$ decays as well as with the relevant experimental data. Our prediction is in agreement with the LEP measurement and is consistent with the standard-model calculation of the exclusive modes. We discuss the impact from physics beyond the Standard Model.

15 pages, 4 figures, 5 tables