Time Dependent $B_s^0-\overline{B_s^0}$ Oscillations Using Exclusively Reconstructed $D_s^{+}$ Decays at SLD

Abstract

We set a preliminary 95% C.L. exclusion on the oscillation frequency of $B_s^0-\overline{B_s^0}$ mixing using a sample of 400,000 hadronic $Z^0$ decays collected by the SLD experiment at the SLC during the 1996-98 run. In this analysis, $B_s^0$ mesons are partially reconstructed by combining a fully reconstructed $D_s$ with other $B_s^0$ decay tracks. The $D_s$ decays are reconstructed via the $\varphi \pi$ and $K^{\ast }K$ channels. The $b$-hadron flavor at production is determined by exploiting the large forward-backward asymmetry of polarized $Z^0\to b\bar{b}$ decays as well as information from the hemisphere opposite to the reconstructed B decay. The flavor of the $B_s^0$ at the decay vertex is determined by the charge of the $D_s$. A total of 361 candidates passed the final event selection cuts. This analysis excludes the following values of the $B_s^0-\overline{B_s^0}$ mixing oscillation frequency: $\Delta m_s<1.5$ ps${}^{-1}$, $2.6<\Delta m_s<4.9$ ps${}^{-1}$, and $10.8<\Delta m_s<13.5$ ps${}^{-1}$ at the 95% confidence level.

24 pages, 9 figures, contributed to the XXX International Conference on High Energy Physics (ICHEP 2000), Osaka, Japan, 27 July - 2 August, 2000