Light-cone sum rules for B → π form factors revisited

Abstract

We reconsider and update the QCD light-cone sum rules for B → π form factors. The gluon radiative corrections to the twist-2 and twist-3 terms in the correlation functions are calculated. The b-quark mass is employed, instead of the one-loop pole mass used in the previous analyses. The light-cone sum rule for f +Bπ(q 2) is fitted to the measured q 2-distribution in B → πlν l, fixing the input parameters with the largest uncertainty: the Gegenbauer moments of the pion distribution amplitude. For the B → π vector form factor at zero momentum transfer we predict f +Bπ(0) = 0.26 +0.04-0.03. Combining it with the value of the product |V ubf +Bπ(0)| extracted from experiment, we obtain |V ub| = (3.5±0.4±0.2±0.1) × 10 -3. In addition, the scalar and penguin B → π form factors f 0Bπ(q 2) and f TBπ(q 2) are calculated.