The B ˉ documentclass[12pt]{minimal} usepackage{amsmath} usepackage{wasysym} usepackage{amsfonts} usepackage{amssymb} usepackage{amsbsy} usepackage{mathrsfs} usepackage{upgreek} setlength{oddsidemargin}{-69pt} egin{document}$$ overline{B} $$end{document} → π form factors from QCD and their impact on |V _ub |

摘要

A bstract We revisit light-cone sum rules with pion distribution amplitudes to determine the full set of local B ˉ documentclass[12pt]{minimal} usepackage{amsmath} usepackage{wasysym} usepackage{amsfonts} usepackage{amssymb} usepackage{amsbsy} usepackage{mathrsfs} usepackage{upgreek} setlength{oddsidemargin}{-69pt} egin{document}$$ overline{B} $$end{document} → π form factors. To this end, we determine all duality threshold parameters from a Bayesian fit for the first time. Our results, obtained at small momentum transfer q ~(2), are extrapolated to large q ~(2)where they agree with precise lattice QCD results. We find that a modification to the commonly used BCL parametrization is crucial to interpolate the scalar form factor between the two q ~(2)regions. We provide numerical results for the form factor parameters — including their covariance — based on simultaneous fit of all three form factors to both the sum rule and lattice QCD results. Our predictions for the form factors agree well with measurements of the q ~(2)spectrum of the semileptonic decay B ˉ 0 → π + ? ? ν ˉ ? documentclass[12pt]{minimal} usepackage{amsmath} usepackage{wasysym} usepackage{amsfonts} usepackage{amssymb} usepackage{amsbsy} usepackage{mathrsfs} usepackage{upgreek} setlength{oddsidemargin}{-69pt} egin{document}$$ {overline{B}}^0o {pi}^{+}{mathrm{ell}}^{-}{overline{u}}_{mathrm{ell}} $$end{document} . From the world average of the latter we obtain | V _( ub )| = (3 . 77 ± 0 . 15) · 10~( ? 3), which is in agreement with the most recent inclusive determination at the 1 σ level.