B → Kl+l- decay at large hadronic recoil

We predict the amplitude of the B → Kl+l- decay in the region of the dilepton invariant mass squared 0 < q2≤ m2J/ψ, that is, at large hadronic recoil. The B → K form factors entering the factorizable part of the decay amplitude are obtained from QCD light-cone sum rules. The nonlocal effects, generated by the four-quark and penguin operators combined with the electromagnetic interaction, are calculated at q2<0, far below the hadronic thresholds. For hard-gluon contributions we employ the QCD factorization approach. The soft-gluon nonfactorizable contributions are estimated from QCD light-cone sum rules. The result of the calculation is matched to the hadronic dispersion relation in the variable q2, which is then continued to the kinematical region of the decay. The overall effect of nonlocal contributions in B → Kl+l- at large hadronic recoil is moderate. The main uncertainty of the predicted B → Kl+l- partial width is caused by the B → K form factors. Furthermore, the isospin asymmetry in this decay is expected to be very small. We investigate the deviation of the observables from the Standard Model predictions by introducing a generic new physics contribution to the effective Hamiltonian.