Search for Second-Generation Leptoquark Pairs in $\overline{p}\mathit{p}$ Collisions at $\surd \mathit{s}=1.8\mathrm{}\mathrm{TeV}$

We have searched for second-generation leptoquark (LQ) pairs in the $\mu \mu +\mathrm{jets}$ channel using $94\pm 5{\mathrm{pb}}^{-1\mathrm{}}$ of $\overline{p}p$ collider data collected by the D0 experiment at the Fermilab Tevatron during 1993–1996. No evidence for a signal is observed. These results are combined with those from the $\mu \nu +\mathrm{jets}$ and $\nu \nu +\mathrm{jets}$ channels to obtain $95\%$ confidence level (C.L.) upper limits on the LQ pair production cross section as a function of mass and $\beta$, the branching fraction of a LQ decay into a charged lepton and a quark. Lower limits of $200\left(180\right)\mathrm{GeV}{/c}^2$ for $\beta =1\mathrm{}\left(\frac{1}{2}\right)$ are set at the $95\%$ C.L. on the mass of scalar LQ. Mass limits are also set on vector leptoquarks as a function of $\beta$.