Two-loop Corrections to the B to pi Form Factor from QCD Sum Rules on the Light-Cone and |V(ub)|

TL;DR

This paper computes two-loop QCD corrections to the B to pi form factor using light-cone sum rules, finds cancellations reducing correction sensitivity, and refines the |V(ub)| CKM matrix element estimate.

Contribution

It provides the first calculation of leading-twist O(alphas^2 beta0) corrections to the B to pi form factor within the light-cone sum rules framework, highlighting correction cancellations.

Findings

Two-loop corrections partially cancel, reducing their impact.

The form factor calculation is insensitive to these higher-order corrections.

An improved |V(ub)| value is obtained from updated experimental data.

Abstract

We calculate the leading-twist O(alphas^2 beta0) corrections to the B to pi transition form factor f+(0) in light-cone sum rules. We find that, as expected, there is a cancellation between the O(alphas^2 beta0) corrections to fB f+(0) and the large corresponding corrections to fB, calculated in QCD sum rules. This suggests the insensitivity of the form factors calculated in the light-cone sum rules approach to this source of radiative corrections. We further obtain an improved determination of the CKM matrix element |V(ub)|, using latest results from BaBar and Belle for f+(0)|V(ub)|.