Search for the W-exchange decays B0 --> Ds(*)- Ds(*)+

Abstract

We report a search for the decays $B^0\to D_s^{-}{D}_s^{+}$, $B^0\to D_s^{\ast -}{D}_s^{+}$, $B^0\to D_s^{\ast -}{D}_s^{\ast +}$ in a sample of 232 million ${\rm Y}(4S)$ decays to \BBb ~pairs collected with the \babar detector at the PEP-II asymmetric-energy $e^{+}{e}^{-}$ storage ring. We find no significant signal and set upper bounds for the branching fractions: $\mathcal{B}(B^0\to D_s^{-}{D}_s^{+})<1.0\times 10^{-4},\mathcal{B}(B^0\to D_s^{\ast -}{D}_s^{+})<1.3\times 10^{-4}$ and $\mathcal{B}(B^0\to D_s^{\ast -}{D}_s^{\ast +})<2.4\times 10^{-4}$ at 90% confidence level.

8 pages, 2 figures, submitted to PRD-RC