$B\ensuremath{\rightarrow}{K}^{*}$ form factors from flavor data to QCD and back

$B \to K^{*}$ form factors from flavor data to QCD and back

Christian Hambrock, Gudrun Hiller, Stefan Schacht, and Roman Zwicky

Phys. Rev. D 89, 074014 – Published 4 April 2014

Abstract

Sufficient control of transition form factors is a vital ingredient for the precision flavor programs including the nearer term searches at the Large Hadron Collider and the forthcoming Belle II experiment. We improve on existing methods to extract $B \to K^{*}$ form factor ratios at low hadronic recoil from $B \to K^{*} ℓ^{+} ℓ^{-}$ data on the angular observables $F_{L}$ , $A_{T}^{(2)}$ and $P_{4}^{'}$ by adding heavy quark symmetry-based constraints and by investigating the cross talk between low and large recoil. The data-extracted form factor ratios (i) provide benchmarks for the lattice and light-cone sum rule predictions, the latter of which have been updated including improved uncertainty estimations, and (ii) allow us to improve the predictions for benchmark observables. We find that present data on the forward-backward asymmetry $A_{FB}$ and the angular observable $P_{5}^{'}$ at low recoil are in good agreement with the Standard Model.