A study of B$_s^0$ meson oscillation using D$_{\rm s}^-$-lepton correlations

Abstract.

From data collected around the Z resonance by the OPAL detector at LEP, a sample of B$_s^0$ decays was obtained using D$_s^-}\ell^+$ combinations, where the $D_s^-$ was fully reconstructed in the $\phi\pi^-, \mathrm{K}^{*0}\mathrm{K}^-$ and $\mathrm{K}^0_{\mathrm{S}}\mathrm{K}^-$ decay channels or partially reconstructed in the $\phi\ell^-\bar{\nu}(\mathrm{X})$ decay channel. These events were used to study $\mathrm{B_s^0}$ oscillation. The flavor (b or $\bar{b}$) at decay was determined from the lepton charge while the flavor at production was determined from a combination of techniques. The expected sensitivity of the experiment is 4.1 ps$^{-1}$. The experiment was not able to resolve the oscillatory behavior, and we deduced that the B$_s^0$ oscillation frequency $\Delta m_s > 1.0$ ps$^{-1}$ at the 95% confidence level.