engleski

Light-cone sum rules for B ---> pi form factors revisited

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 overline-MS 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(q2) is fitted to the measured q2-distribution in B → πlνl, 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 |Vubf+Bπ(0)| extracted from experiment, we obtain |Vub| = (3.5±0.4±0.2±0.1) × 10−3. In addition, the scalar and penguin B → π form factors f0Bπ(q2) and fTBπ(q2) are calculated.

light cone ; sum rule ; form factor

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