Determination of ‖Vts‖ fromD→K*lν andB→K*γ data via heavy quark symmetry and perturbative QCD

We use heavy quark effective theory (HQET) and perturbative QCD to study the heavy-meson–light-vector-meson transitions involved in D and B decays. HQET is used to relate the measured D→${\mathit{K}}^{\mathrm{*}}$lν vector and axial-vector form factors at four-momentum transfer ${\mathit{q}}^2$=0 to the B→${\mathit{K}}^{\mathrm{*}}$γ tensor and axial-tensor form factors at ${\mathit{q}}^2$=16.5 ${\mathrm{GeV}}^2$. Perturbative QCD is then used to find matching conditions for the B-meson form factors at ${\mathit{q}}^2$=0. A five parameter ‘‘vector-dominance’’-type fit of the two HQET form factors, consisting of single pole, double pole, and subtraction terms, is used to match the data at ${\mathit{q}}^2$=16.5 ${\mathrm{GeV}}^2$ to QCD at ${\mathit{q}}^2$=0. The values at ${\mathit{q}}^2$=0 are compared with recent data on the exclusive rate for B→${\mathit{K}}^{\mathrm{*}}$γ decay to extract a value for the Cabibbo-Kobayashi-Maskawa matrix element ‖${\mathit{V}}_{\mathit{t}\mathit{s}}$‖=0.026, with 23% experimental uncertainty, and 29% theoretical uncertainty from higher order QCD effects and violations of heavy quark symmetry.