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

TL;DR

This paper reports precise measurement of the B0bar --> Ds-D+ decay branching fraction and sets an upper limit for the B0bar --> Ds+Ds- decay, using a large data sample from the Belle experiment.

Contribution

First precise measurement of B0bar --> Ds-D+ branching fraction and the establishment of an upper limit for B0bar --> Ds+Ds- decay.

Findings

Br(B0bar --> Ds-D+) = (7.5 +- 0.2 (stat) +- 0.8 (syst) +- 0.8 (Br's)) x 10^(-3)

No significant signal for B0bar --> Ds+Ds-; upper limit set at 3.6 x 10^(-5) (90% C.L.)

Large data sample of 449 million BBbar pairs used for analysis

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.).