B → V l+l− in the Standard Model from Light-Cone Sum Rules

Preprint number: CP3-Origins-2015-10 DNRF90 and DIAS-2015-10
Authors: Aoife Bharucha (Technische Universität München & CNRS), David M. Straub (Excellence Cluster Universe, Technische Universität München), and Roman Zwicky (University of Edinburgh & CP3-Origins & DIAS)
External link: arXiv.org

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We present Bq → ρ, Bq → ω, Bq → K∗, Bs → K∗ and Bs → φ form factors from light-cone sum rules using updated hadronic input parameters. It is argued that the, generally valid, equations of motion constrain the uncertainty of tensor-to-vector form factor ratio. This improves the prediction of zeros of helicity amplitudes which is of major importance for B → K∗ll angular observables. We provide easy-to-use fits to the LCSR results, including the full error correlation matrix, in all modes at low q^2 as well as combined fits to LCSR and lattice results covering the entire kinematic range for Bq → K∗, Bs → K∗ and Bs → φ. The error correlation matrix avoids the problem of overestimating the uncertainty in phenomenological applications. Using the new form factors and recent computations of non-factorisable contributions we provide Standard Model predictions for B → K∗γ as well as B → K∗l+l− and Bs → φμ+μ− at low dilepton invariant mass. Employing our B → (ρ, ω) form factor results we extract the CKM element |Vub| from the semileptonic decays B → (ρ,ω)lν, and find good agreement with other exclusive determinations.