Nils Offen

Form-factors from light-cone sum rules with B-meson distribution amplitudes

New sum rules for B{yields}{pi},K and B{yields}{rho},K* form factors are derived from the correlation functions expanded near the light cone in terms of B-meson distribution amplitudes. The contributions of quark-antiquark and quark-antiquark-gluon components in the B meson are taken into account. Models for the B-meson three-particle distribution amplitudes are suggested, based on QCD sum rules in heavy-quark effective theory. Employing the new light-cone sum rules, we calculate the form factors at small momentum transfers, including SU(3)-violation effects. The results agree with the predictions of the conventional light-cone sum rules.

Light Cone Sum Rules for the pi0-gamma*-gamma Form Factor Revisited

We provide a theoretical update of the calculations of the pi0-gamma*-gamma form factor in the LCSR framework, including up to six polynomials in the conformal expansion of the pion distribution amplitude and taking into account twist-six corrections related to the photon emission at large distances. The results are compared with the calculations of the B-> pi l nu decay and pion electromagnetic form factors in the same framework. Our conclusion is that the recent BaBar measurements of the pi0-gamma*-gamma form factor at large momentum transfers are consistent with QCD, although they do suggest that the pion DA may have more structure than usually assumed.

B-meson distribution amplitude from the B → π form factor

Abstract Employing the light-cone sum rule approach in QCD, we relate the B -meson distribution amplitude to the B → π form factor at zero momentum transfer. In leading order, the sum rule is converted into a simple expression for the inverse moment λ B of the distribution amplitude ϕ + B . Using as an input the B → π form factor calculated from the light-cone sum rule in terms of pion distribution amplitudes, we obtain an estimate: λ B = 460 ± 160 MeV . We investigate how this result is modified by the B -meson three-particle distribution amplitudes.

BELLE Data on the

We extend our analysis of the

\pi^0 \gamma* \gamma

\pi^0\gamma^*\gamma

Form Factor: A Game Changer?

form factor by including a comparison with the new BELLE data. The necessity of new precision measurements in a broad interval of momentum transfers is emphasized.

|Vub| determination using B → π form factor from light-cone sum rule

A determination of |Vub| from the exclusive semileptonic B → πlvl decay is presented, using the new calculation of the B → π form factor fB+π(0) from QCD light-cone sum rule with O(αs) accuracy in twist-2 and twist-3 terms and employing the MS scheme for the b-quark mass.