Search for time-dependent<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msubsup><mml:mrow><mml:mi>B</mml:mi></mml:mrow><mml:mrow><mml:mi>s</mml:mi></mml:mrow><mml:mrow><mml:mn>0</mml:mn></mml:mrow></mml:msubsup></mml:mrow><mml:mo>−</mml:mo><mml:mrow><mml:mrow><mml:mover><mml:mrow><mml:mrow><mml:msubsup><mml:mrow><mml:mi>B</mml:mi></mml:mrow><mml:mrow><mml:mi>s</mml:mi></mml:mrow><mml:mrow><mml:mn>0</mml:mn></mml:mrow></mml:msubsup></mml:mrow></mml:mrow><mml:mrow><mml:mi>¯</mml:mi></mml:mrow></mml:mover></mml:mrow></mml:mrow></mml:math>oscillations using a vertex charge dipole technique

We report a search for ${B}_{s}^{0}\ensuremath{-}\overline{{B}_{s}^{0}}$ oscillations using a sample of $400000$ hadronic ${Z}^{0}$ decays collected by the SLD experiment. The analysis takes advantage of the electron beam polarization as well as information from the hemisphere opposite that of the reconstructed B decay to tag the B production flavor. The excellent resolution provided by the pixel CCD vertex detector is exploited to cleanly reconstruct both B and cascade D decay vertices, and tag the B decay flavor from the charge difference between them. We exclude the following values of the ${B}_{s}^{0}\ensuremath{-}\overline{{B}_{s}^{0}}$ oscillation frequency: $\ensuremath{\Delta}{m}_{s}&lt;4.9{\mathrm{ps}}^{\ensuremath{-}1}$ and $7.9&lt;\ensuremath{\Delta}{m}_{s}&lt;10.3{\mathrm{ps}}^{\ensuremath{-}1}$ at the $95%$ confidence level.