The $\bar{B}\to \pi$ form factors from QCD and their impact on $|V_{ub}|$

Understand

We revisit light-cone sum rules with pion distribution amplitudes to determine the full set of local $B \to \pi$ form factors.

• To this end, we determine all duality threshold parameters from a Bayesian fit for the first time.
• Our results, obtained at small momentum transfer $q^2$, are extrapolated to large $q^2$ where they agree with precise lattice QCD results.
• We find that a modification to the commonly used BCL parametrization is crucial to interpolate the scalar form factor between the two $q^2$ regions.