Resummation of running coupling effects in semileptonic B meson decays and extraction of |V$_{cb}$|

We present a determination of |V_{cb}| from semileptonic B decays that includes resummation of supposedly large perturbative corrections originating from the running of the strong coupling. We argue that the low value of the BLM scale found previously for inclusive decays is a manifestation of the renormalon divergence of the perturbative series starting already in third order. A reliable etermination of |V_{cb}| from inclusive decays is possible if one either uses a short distance b quark mass or eliminates all unphysical mass parameters in terms of measured observables, such that all infra-red contributions of order 1/m_b cancel explicitly. We find that using the \overline{\rm MS} running mass significantly reduces the perturbative coefficients already in low orders. The resummation of running coupling effects is numerically important and increases the decay rate by (20-40)\%, when calculated with the same input parameters as without resummation. The scheme- and scale-dependence of the results is reduced. For a semileptonic branching ratio of 10.9\% we obtain |V_{cb}|(\tau_B/1.50\,{\rm ps})^{1/2}= 0.041\pm 0.002 from inclusive decays, in good agreement with the value extracted from exclusive decays.