Standard Model predictions for B -> Kll with form factors from lattice QCD

We calculate, for the first time using unquenched lattice QCD form factors, the Standard Model differential branching fractions $dB/dq^2(B \to Kll)$ for $l=e, μ, τ$ and compare with experimental measurements by Belle, BABAR, CDF, and LHCb. We report on $\mathcal{B}(B \to Kll)$ in $q^2$ bins used by experiment and predict $\mathcal{B}(B \to K ττ) = (1.44 \pm 0.15) 10^{-7}$. We also calculate the ratio of branching fractions $R^μ_e = 1.00023(63)$ and predict $R^τ_l = 1.159(40)$, for $l=e, μ$. Finally, we calculate the "flat term" in the angular distribution of the differential decay rate $F_H^{e, μ, τ}$ in experimentally motivated $q^2$ bins.

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