We present the results of a search for third generation leptoquark (LQ) pairs in $110\pm 8{\mathrm{pb}}^{-1\mathrm{}}$of $\overline{p}p$ collisions at $\sqrt{s}=1.8\mathrm{}\mathrm{TeV}$ recorded by the Collider Detector at Fermilab. We assume third generation leptoquarks decay to a $\tau$ lepton and a $b$ quark with branching ratio $\beta$. We observe one candidate event, consistent with standard model background expectations. We place upper limits on $\sigma (\overline{p}p\to \mathrm{LQ}\overline{\mathrm{LQ}})̇{\beta }^2$ as a function of the leptoquark mass $M_{\mathrm{LQ}}$. We exclude at 95% confidence level scalar leptoquarks with $M_{\mathrm{LQ}}<99\mathrm{}\mathrm{GeV}{/c}^2$, gauge vector leptoquarks with $M_{\mathrm{LQ}}<225\mathrm{}\mathrm{GeV}{/c}^2$, and nongauge vector leptoquarks with $M_{\mathrm{LQ}}<170\mathrm{}\mathrm{GeV}{/c}^2$ for $\beta =1\mathrm{}$.

• Received 17 December 1996

DOI:https://doi.org/10.1103/PhysRevLett.78.2906