A Study of the Rare Decays $B^0\to D_s^{(\ast )+}{\pi }^{-}$ and $B^0\to D_s^{(\ast )-}{K}^{+}$

Abstract

We report evidence for the decays $B^0\to D_s^{+}{\pi }^{-}$ and $B^0\to D_s^{-}{K}^{+}$ and the results of a search for $B^0\to D_s^{\ast +}{\pi }^{-}$ and $B^0\to D_s^{\ast -}{K}^{+}$ in a sample of 84 milion Y(4S) decays into $B\bar{B}$ pairs collected with the BaBar detector at the PEP II asymmetric-energy $e^{+}{e}^{-}$ storage ring. We measure the branching fraction Br($B^0\to D_s^{+}{\pi }^{-})=3.2\pm 0.9(stat.)\pm 1.0(syst.)$. and Br($B^0\to D_s^{+}{\pi }^{-})=3.2\pm 1.0(stat.)\pm 1.0(syst.)$. We also set 90% C.L. limits BR($B^0\to D_s^{\ast +}{\pi }^{-})<4.1\times 10^{-5}$ at 90% C.L and BR($B^0\to D_s^{\ast -}{K}^{+})<2.5\times 10^{-5}$ at 90% C.L.

7 pages, 3 encapsulated postscript figures, submitted to PRL