Measurement and interpretation of fermion-pair production at LEP energies of 183-GeV and 189-GeV

An analysis of the data collected in 1997 and 1998 with the DELPHI detector at e + e − collision energies close to 183 and 189 GeV was performed in order to extract the hadronic and leptonic fermion-pair cross-sections, as well as the leptonic forward–backward asymmetries and angular distributions. The data are used to put limit on contact interactions between fermions, the exchange of R-parity violating SUSY sneutrinos, Z′ bosons and the existence of gravity in extra dimensions.