Predictions on B-->πl¯νl, D-->πl¯νl, and D-->Kl¯νl from QCD light-cone sum rules

The f⁺ form factors of the B-->π, D-->π and D-->K transitions are calculated from QCD light-cone sum rules (LCSRs) and used to predict the widths and differential distributions of the exclusive semileptonic decays B-->πl¯ν_l, D-->πl¯ν_l and D-->Kl¯ν_l, where l=e,μ. The current theoretical uncertainties are estimated. The LCSR results are found to agree with the results of lattice QCD calculations and with experimental data on exclusive semileptonic D decays. Comparison of the LCSR prediction of B-->πl¯ν_l with the CLEO measurement yields a value of \|V_ub\| in agreement with other determinations.