Limits on the production of scalar leptoquarks from Z (0) decays at LEP

A search has been made for pairs and for single production of scalar leptoquarks of the first and second generations using a data sample of 392000 Z0 decays from the DELPHI detector at LEP 1. No signal was found and limits on the leptoquark mass, production cross section and branching ratio were set. A mass limit at 95% confidence level of 45.5 GeV/c2 was obtained for leptoquark pair production. The search for the production of a single leptoquark probed the mass region above this limit and its results exclude first and second generation leptoquarks D0 with masses below 65 GeV/c2 and 73 GeV/c2 respectively, at 95% confidence level, assuming that the D0lq Yukawa coupling alpha(lambda) is equal to the electromagnetic one. An upper limit is also given on the coupling alpha(lambda) as a function of the leptoquark mass m(D0)

A measurement of the charge asymmetry in e+e- to bb- and a search for new quarks at PETRA

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A Study of heavy flavor production using muons in hadronic Z0 decays

Contains fulltext : 125113.pdf (preprint version ) (Open Access

A DIRECT SEARCH FOR NEW CHARGED HEAVY LEPTONS AT LEP

This is the post-print version of the Article - Copyright @ 1990 ElsevierResults are presented from a search for a new charged heavy lepton in e+e− annihilation. The data were taken with the OPAL detector at LEP during a scan of the Z0 resonance. Two independent search techniques were used, one looking for events with large missing energy and missing momentum transverse to the beam, and the other for events with isolated energetic leptons. Two candidate events, consistent with expected background, were found in the first search; none was found in the second. These results allow the exclusion at the 95% confidence level of a charged heavy lepton of mass less than 44.3 GeV/c2 if it is assumed to have a massless neutrino partner. Limits are also presented for the case of a massive neutrino.This study is supported by The Bundesministerium f'tir Forschung und Technologie, FRG, The Department of Energy, USA, The Institut de Recherche Fondamentale du Commissariat a l'Energie Atomique, The Israeli Ministry of Science, The Minerva Gesellschaft, The National Science Foundation, USA, The Natural Sciences and Engineering Research Council, Canada, The Japanese Ministry of Education, Science and Culture (the Monbusho) and a grant under the Monbusho International Science Research Program, The Science and Engineering Research Council, UK and The A.P. Sloan Foundation