Search for first-generation scalar and vector leptoquarks
V. M. Abazov, B. Abbott, A. Abdesselam, M. Abolins, V. Abramov, B. S. Acharya, D. L. Adams, M. R. Adams, Shuvro Ahmed, G. D. Alexeev, Gilvan Augusto Alves, N. Amos, E. W. Anderson, Y. Arnoud, M. M. Baarmand, V. Babintsev, L. Babukhadia, T. C. Bacon, A. Baden, B.Yu. Baldin · Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D. Particles and fields · 2001
We describe a search for the pair production of first-generation scalar and vector leptoquarks in the $\mathrm{eejj}$ and $e\ensuremath{ u}\mathrm{jj}$ channels by the D\O{} Collaboration. The data are from the 1992--1996 $p\overline{p}$ run at $\sqrt{s}=1.8 \mathrm{TeV}$ at the Fermilab Tevatron collider. We find no evidence for leptoquark production; in addition, no kinematically interesting events are observed using relaxed selection criteria. The results from the $\mathrm{eejj}$ and $e\ensuremath{ u}\mathrm{jj}$ channels are combined with those from a previous D\O{} analysis of the $\ensuremath{ u}\ensuremath{ u}\mathrm{jj}$ channel to obtain 95% confidence level (C.L.) upper limits on the leptoquark pair-production cross section as a function of mass and of $\ensuremath{\beta},$ the branching fraction to a charged lepton. These limits are compared to next-to-leading-order theory to set 95% C.L. lower limits on the mass of a first-generation scalar leptoquark of 225, 204, and 79 $\mathrm{GeV}{/c}^{2}$ for $\ensuremath{\beta}=1,$ $\frac{1}{2},$ and 0, respectively. For vector leptoquarks with gauge (Yang-Mills) couplings, 95% C.L. lower limits of 345, 337, and 206 $\mathrm{GeV}{/c}^{2}$ are set on the mass for $\ensuremath{\beta}=1,$ $\frac{1}{2},$ and 0, respectively. Mass limits for vector leptoquarks are also set for anomalous vector couplings.