Time-dependent B s0- B¯s0 mixing using inclusive and semileptonic B decays at SLD

We have searched for time-dependent B _s⁰- B¯_s⁰ mixing using a sample of 400 000 hadronic Z ⁰ decays collected by the SLD experiment at the SLC. The analyses take advantage of the excellent vertexing efficiency and resolution of the pixel-based CCD Vertex Detector which provides a B decay length resolution of approximately 100 μm. All analyses determine the B hadron flavor at production by exploiting the large forward-backward asymmetry of polarized Z⁰→ bb¯ decays. This flavor tag is enhanced by incorporating additional information from the hemisphere opposite that of the reconstructed B decay. In one analysis, B decay vertices are reconstructed inclusively with a topological technique, and separation between B _s⁰ and B¯_s⁰ decays is based on the reconstruction of a "charge dipole" of the topological vertices to exploit the B _s⁰→D _s^- cascade charge structure. The other two analyses select semileptonic decays to tag the B flavor at decay and reconstruct the B decay vertex by intersecting the lepton with either all tracks in the nearest jet or the trajectory of a topologically reconstructed D vertex. The three analyses are combined to exclude the following values of the oscillation frequency: Δ m_s<5.3 and 6.0 ps^-1< Δm _s<11.5 ps^-1. Future prospects are outlined.