Search for contact interactions in the reactionse ⁺ e ⁻→l ⁺ l ⁻ ande ⁺ e ⁻→γγ

Abstract

Contact interactions are searched for using the differential cross sections for the reactionse ⁺ e ⁻→e ⁺ e ⁻,e ⁺ e ⁻→µ ⁺ µ ⁻,e ⁺ e ⁻→τ ⁺ τ ⁻ ande ⁺ e ⁻→γγ measured at 12 energies around theZ peak and corresponding to about 20 pb⁻¹ of cumulated luminosity. Four-fermion contact term models assuming various chiralities of lepton currents are fitted to the lepton data and lower limits on the energy scale Λ of such terms are set at 95% c.l. The limits vary in the range 0.9–4.7 TeV, depending on the model and on the lepton flavour. Theeeγγ contact terms are searched for assuming various chiralities. Limits on the energy scale Λ between 79 and 130 GeV are extracted from the data. The results are compared and combined with those reported at lower energies.