Abstract
We present B
_{
q
} → ρ, B
_{
q
} → ω, B
_{
q
} → K
^{∗}, B
_{
s
} → K
^{∗} and B
_{
s
} → ϕ form factors from lightcone sum rules (LCSR) at O(αs) for twist2 and 3 and O(α0s)
for twist4 with updated hadronic input parameters. Three asymptotic
lightcone distribution amplitudes of twist4 (and 5) are determined,
necessary for the form factors to obey the equations of motion. It is
argued that the latter constrain the uncertainty of tensortovector
form factor ratios thereby improving the prediction of zeros of helicity
amplitudes of major importance for B → K
^{∗}ℓℓ angular observables. We
provide easytouse 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 B
_{
q
} → K
^{∗}, B
_{
s
} → K
^{∗} and B
_{
s
} → ϕ. The error correlation matrix avoids
the problem of overestimating the uncertainty in phenomenological
applications. Using the new form factors and recent computations of
nonfactorisable contributions we provide Standard Model predictions for
B → K
^{∗}γ as well as B → K
^{∗}ℓ^{+}ℓ^{−} and B
_{
s
} → ϕμ
^{+}
μ
^{−} at low dilepton invariant mass. Employing our B → (ρ,ω) form factor results we extract the CKM element V
_{ub} from the semileptonic decays B → (ρ, ω)ℓν and find good agreement with other exclusive determinations.
Original language  English 

Article number  98 
Pages (fromto)  162 
Number of pages  62 
Journal  Journal of High Energy Physics 
Volume  N/A 
DOIs  
Publication status  Published  16 Aug 2016 
Keywords
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Profiles

Roman Zwicky
 School of Physics and Astronomy  Personal Chair of Theoretical High Energy Physics
Person: Academic: Research Active