Search for First Generation Scalar Leptoquark Pairs in $\mathit{p}\overline{\mathit{p}}$ Collisions at $\sqrt{\mathit{s}}=1.8\mathrm{TeV}$

We have searched for first generation scalar leptoquark (LQ) pairs in the $e\nu +\mathrm{jets}$ channel using $p\overline{p}$ collider data $\left(\int L\mathrm{dt}\approx 115{\mathrm{pb}}^{-1\mathrm{}}\right)$ collected by the D0 experiment at the Fermilab Tevatron during 1992–1996. The analysis yields no candidate events. We combine the results with those from the $ee+\mathrm{jets}$ 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 of $\beta$, the branching fraction to a charged lepton. Comparing with the next-to-leading order theory, we set 95% C.L. lower limits on the LQ mass of 225, 204, and $79\mathrm{GeV}{/c}^2$ for $\beta =1\mathrm{}$, $\frac{1}{2}$, and 0, respectively.