European Organisation for Nuclear Research

A search for pair-produced scalar fermions under the assumption that R-parity is not conserved has been performed using data samples corresponding to an integrated luminosity of about 700 pb collected with the OPAL detector at LEP above the Z peak, at centre-of-mass energies up to √ s = 209 GeV. An important consequence of Rparity violation is that the lightest supersymmetric particle is expected to be unstable. Searches for R-parity violating decays of charged sleptons, sneutrinos and squarks have been performed under the assumptions that the lightest supersymmetric particle decays promptly and that only one of the R-parity violating couplings is dominant for each of the decay modes considered. Such processes would yield multi-leptons, jets plus leptons or multi-jets, with or without missing energy, in the final state. No significant excess of such events has been observed. Limits on the production cross-sections of scalar fermions in R-parity violating scenarios are obtained. Mass exclusion regions are also presented in the framework of the Constrained Minimal Supersymmetric Standard Model. This note describes preliminary OPAL results