Measurement of the branching fraction for D - s → φπ -

Abstract We present a model-independent measurement of B(D s − → Φπ − ) B(D 0 → K − π + ) by partially reconstructing the decay B 0 → D ∗+ D s ∗− . Using data collected with the CLEO II detector at CESR, we determine B(D s − → Φπ − ) B(D 0 → K − π + ) = 0.92 ± 0.20 (stat.) ± 0.11(syst.) . Our measurement of B ( D 0 → K − π + ) then gives B ( D s − → Φπ − ) = (3.59 ± 0.77 ± 0.48)%.