Search for pair production of first-generation leptoquarks in p pbar collisions at sqrt(s)=1.96 TeV

TL;DR

This paper reports a search for first-generation leptoquark pair production at the Fermilab Tevatron, setting new mass limits based on data analysis of electron and jet final states, consistent with the Standard Model.

Contribution

It provides the first combined limits on scalar and vector leptoquark masses using ~1 fb-1 of data, improving previous results from earlier Tevatron runs.

Findings

Set 95% C.L. lower limits on scalar LQ mass: 299 GeV (beta=1), 284 GeV (beta=0.5), 216 GeV (beta=0.02)

Set lower limits on vector LQ masses from 357 GeV to 464 GeV for beta=0.5

Data is consistent with Standard Model expectations.

Abstract

A search for pair production of first-generation leptoquarks LQ is performed with data collected by the D0 experiment in p pbar collisions at sqrt(s)=1.96 TeV at the Fermilab Tevatron Collider. In a sample of data corresponding to ~1 fb-1, the search has been performed on the final states with two electrons and two jets or one electron, two jets and missing transverse energy. We find our data consistent with standard model expectations. The results are combined with those found in a previous analysis of events with two jets and missing transverse energy to obtain scalar LQ mass limits. We set 95% C.L. lower limits on a scalar LQ mass of 299 GeV, 284 GeV and 216 GeV for beta=1, beta=0.5 and beta=0.02 respectively, where beta is the LQ branching ratio in the eq channel. This improves the results obtained with a lower luminosity sample from Run II of the Tevatron. Lower limits on vector LQ masses with different couplings from 357 GeV to 464 GeV for beta=0.5 are also set using this analysis.