Search for pair-produced leptoquarks in e+e- interactions at sqrt(s) = 189 - 209 GeV

TL;DR

This paper reports a search for pair-produced leptoquarks in electron-positron collisions at energies between 189 and 209 GeV, setting new mass limits and improving previous constraints.

Contribution

First search for leptoquark pair production at LEP energies with improved mass limits and analysis of specific decay channels.

Findings

No evidence for leptoquark production was observed.

Mass limits for scalar and vector leptoquarks were established.

Results improve previous LEP limits by 10-25 GeV.

Abstract

A search for pair-produced leptoquarks is performed using e+e- collision events collected by the OPAL detector at LEP at centre-of-mass energies between 189 and 209 GeV. The data sample corresponds to a total integrated luminosity of 596 pb^-1. The leptoquarks are assumed to be produced via couplings to the photon and the Z0. For a given search channel only leptoquark decays involving a single lepton generation are considered. No evidence for leptoquark pair production is observed. Lower limits on masses for scalar and vector leptoquarks are calculated. The results improve most of the LEP limits derived from previous searches for the pair production process by 10-25 GeV, depending on the leptoquark quantum numbers.