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T: Teilchenphysik
T 206: Neue Teilchen und Wechselwirkungen 1
T 206.1: Group Report
Monday, March 15, 1999, 16:30–16:55, TE7
Search for new physics in two-fermion production at LEP — •I. Iashvili and S. Riemann — DESY-Zeuthen, Germany
The measurements of hadron and lepton–pair production cross sections and lepton–pair forward–backward asymmetries performed with the L3 detector are used to search for new physics phenomena. New physics effects involving four fermion vertices – contact interactions – are looked for in all channels. Lower limits on the scale Λ of contact interactions in the range 1.7 – 11 TeV are obtained at the 95% confidence level for various models. The limits on the mass of a heavy Z’ boson and Z–Z’ mixing angle θM are set. For e+e−→ e+e−, µ+µ− reactions the exchange of supersymmetric tau-sneutrino is studied. For e+e−→ hadrons production the exchange of virtual leptoquarks and scalar quarks are investigated. No evidence for deviations from the Standard Model expectations is found. Upper limits on the coupling strengths of leptoquarks, scalar quarks and scalar tau-neutrino are derived.