Search for Single Leptoquark Production in Electron-Photon Scattering at 161 and 172 GeV

TL;DR

This paper reports a search for first-generation scalar leptoquarks produced in electron-photon scattering at LEP energies, setting mass limits based on OPAL data from 1996.

Contribution

It introduces a novel search method for single leptoquark production via electron-photon interactions at LEP energies, providing new mass limits.

Findings

Mass limits of 131 GeV for certain coupling and charge assumptions.

No evidence of leptoquark production was observed.

Constraints on leptoquark properties at LEP energies.

Abstract

A search for a first generation scalar leptoquark (LQ) has been performed using the data collected by the OPAL detector in 1996 at e+e- centre-of-mass energies sqrt{s} of 161 and 172 GeV. It is assumed that a single leptoquark can be produced in the process eq->LQ, where the initial state quark originates from a hadronic fluctuation of a quasi-real photon which has been radiated by one of the LEP beams. Lower limits at the 95 % confidence level on the mass of a first generation scalar leptoquark of 131 GeV for beta=0.5 and beta=1, coupling values lambda larger than sqrt{4*pi*alpha_em) and leptoquark charges -1/3 or -5/3 are obtained.