Improved measurement of B0bar --> Ds-D+ and search for B0bar --> Ds+Ds- at Belle

Abstract

We reconstruct B0bar --> Ds-D+ decays using a sample of 449 x 10^6 BBbar pairs recorded by the Belle experiment, and measure the branching fraction to be Br(B0bar --> Ds-D+)=[7.5 +- 0.2(stat) +- 0.8(syst) +- 0.8(Br's)] x 10^(-3). A search for the related decay B0bar --> Ds+Ds- is also performed. Since we observe no statistically significant signal an upper limit on the branching fraction is set at 3.6 x 10^(-5) (90% C.L.).

7 pages, 2 figures, Submitted to Physical Review D, Rapid Communications