Measurement of B-0 -> (Ds-KS0)pi(+) and B+ -> Ds-K+K+ branching fractions

We report a measurement of the B-0 and B+ meson decays to the (Ds-KS0)pi(+) and Ds-K+K+ final states, respectively, using 657 x 10(6)B (B) over bar pairs collected at the gamma(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. Using the D-s(-) -> phi pi(-), K*(892)K-0(-) and (KSK-)-K-0 decay modes for the D-s reconstruction, we measure the following branching fractions: B(B-0 -> (Ds-KS0)pi(+))= [0.47 +/- 0.06(stat) +/- 0.05(syst)] x 10(-4) and B(B+ -> Ds-K+K+)= [0.93 +/- 0.22(stat) +/- 0.10(syst)] x 10(-5). We find the ratio of the branching fraction of B+ -> Ds-K+K+ to that of the analogous Cabibbo-favored B+ -> Ds-K+pi(+) decay to be R-B= 0.054 +/- 0.013(stat) +/- 0.006(syst), which is consistent with the naive factorization model. We also observe a deviation of the DsK invariant-mass distribution from the three-body phase-space model for both studied decays.