Search for contact interactions in the reactions e+e-→l+l- and e+e-→γγ

Contact interactions are searched for using the differential cross sections for the reactions e+e-→e+e-, e+e-→μ+μ-, e+e-→τ+τ- and e+e-→γγ measured at 12 energies around the Z 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. The eeγγ 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. (orig.)