We present results from searches for the top quark pp¯ collisions at the Fermilab Tevatron Collider. The data sample was collected during 1988–89 with the Collider Detector at Fermilab and has an integrated luminosity of 4.1 ${\mathrm{pb}}^{\mathrm{-}1}$. Our previous search for eμ final states for tt¯→eνb μνb¯ decays has been extended to include the ee and μμ channels. In addition, we have searched in each event with a high-transverse-momentum lepton accompanied by hadron jets for a low-transverse-momentum muon as a tag of a bottom quark in tt¯→lνbqq¯b¯ decays. A lower limit on the top-quark mass of 91 GeV/${\mathit{c}}^2$ is obtained at the 95% confidence level, assuming standard model decays.

• Received 16 October 1991

DOI:https://doi.org/10.1103/PhysRevLett.68.447