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arXiv · 0711.0860

Inclusive Measure of |V_ub| with the Analytic Coupling Model

Ugo Aglietti·Francesca Di Lodovico·Giancarlo Ferrera·Giulia Ricciardi
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Abstract

By analyzing B -> X_u l nu_l spectra with a model based on soft-gluon resummation and an analytic time-like QCD coupling, we obtain |V_ub| = (3.76 +-0.13 +- 0.22)*10^(-3), where the first and the second error refers to experimental and theoretical errors, respectively. The V_ub value is obtained from the available measured semileptonic branching fractions in limited regions of the phase-space. The distributions in the lepton energy E_l, the hadron invariant mass m_X, the light-cone momentum P_+ = E_X - p_X, together with the double distributions in (m_X,q^2) and (E_l,s_h^max), are used to select the phase-space regions. The q^2 is the dilepton squared momentum and s_h^max is the maximal m_X^2 at fixed q^2 and E_l. The V_ub value obtained is in complete agreement with the value coming from exclusive B decays and from an over-all fit to the Standard Model parameters. We show that the slight disagreement (up to +2 sigma) with respect to previous inclusive measurements is not related to different choices for the b (and c) masses but to a different modelling of the threshold (Sudakov) region.

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Ugo Aglietti, Francesca Di Lodovico, Giancarlo Ferrera, Giulia Ricciardi. 2009-04-20. Inclusive Measure of |V_ub| with the Analytic Coupling Model. https://doi.org/10.1140/epjc%2Fs10052-008-0817-x

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