B -> K^* Form Factors from Flavor Data to QCD and Back

TL;DR

This paper refines the extraction of B -> K^* form factor ratios from flavor data, incorporating heavy quark symmetry constraints and recoil cross talk, to improve Standard Model predictions and benchmark tests.

Contribution

It introduces enhanced methods for determining B -> K^* form factors using flavor data, integrating symmetry constraints and recoil analysis for better accuracy.

Findings

Form factor ratios serve as benchmarks for lattice and sum rule predictions.

Current data on A_FB and P'_5 align with the Standard Model.

Improved uncertainty estimations enhance predictive reliability.

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 (LHC) and the forthcoming Belle II experiment. We improve on existing methods to extract B -> K^* form factor ratios at low hadronic recoil from B -> 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 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.