Search for ${\mathit{B}}_{\mathit{s}}^0-{\overline{\mathit{B}}}_{\mathit{s}}^0$ Oscillations Using the Semileptonic Decay ${\mathit{B}}_{\mathit{s}}^0\to \mathit{\phi }{\ell }^{+}\mathit{X}\mathit{\nu }$

A search for $B_s^0-{\overline{B}}_s^0$ oscillations is performed in a sample of $B_s^0$ semileptonic decays collected using dilepton triggers at the Tevatron Collider during 1992–1995. The $B_s^0$ is reconstructed using phiv meson-lepton correlations; its initial production flavor is determined with the second lepton in the event. From a signal of 1068 with a $B_s^0$ purity of $61\%$, we obtain a limit on the $B_s^0-{\overline{B}}_s^0$ oscillation frequency of $\Delta m_s>5.8\mathrm{}{\mathrm{ps}}^{-1\mathrm{}}$ at $95\%$ confidence level.