Standard model predictions for B→Kℓ(+)ℓ- 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/dq2(B→Kℓ(+)ℓ(-)) for ℓ=e, µ, τ and compare with experimental measurements by Belle, BABAR, CDF, and LHCb. We report on B(B→Kℓ(+)ℓ(-)) in q2 bins used by experiment and predict B(B→Kτ(+)τ(-))=(1.41±0.15)×10(-7). We also calculate the ratio of branching fractions R(e)(µ)=1.00029(69) and predict R(ℓ)(τ)=1.176(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 q2 bins.