Potential of light-cone sum rules without semiglobal quark-hadron duality

Abstract

This work addresses the calculation of local form factors involved in the theoretical predictions of semileptonic $B$-meson decays at low $q^2$. We present a new approach to the method of QCD light-cone sum rule with $B$-meson light-cone distribution amplitudes. In our strategy, we bypass the semiglobal quark-hadron duality (QHD) approximation which usually contributes an unknown and potentially large systematic error to the prediction of form factors. We trade this improvement for an increased reliance on higher-order contributions in perturbation theory. Unlike the systematic error from semiglobal QHD, truncation errors are assessable and systematically improvable, hence allowing robust predictions of form factors. For the transitions $B\to \pi ,\rho ,K^{(\ast )}$, our predictions agree with the literature for all form factors at $q^2=0$.

Comments: 36 pages, 6 figures, 7 tables. v3: Includes updated bibliography and minor additions in the text. Matches the published version in PRD