Search for R-parity violating decays of scalar fermions at LEP

A search for pair produced scalar fermions with couplings that violate R-pa rity has been performed using a data sample corresponding to an integrated luminosity of 56 pb(-1) at a centre-of-mass energy of root s = 183 GeV coll ected with the OPAL detector at LEP. An important consequence of R-parity b reaking interactions is that the lightest supersymmetric particle is expect ed to be unstable. Searches for R-parity violating decays of charged slepto ns, sneutrinos and stop quarks have been performed under the assumptions th at the lightest supersymmetric particle decays promptly and that only one o f the R-parity violating couplings is dominant for each of the decay modes considered. Such processes would yield multileptons, jets plus leptons or m ulti-jets, with or without missing energy, in the final state. No significa nt excess of such events has been observed. Limits on the production cross- sections of scalar fermions in R-parity violating scenarios are obtained. M ass exclusion regions are also presented in the framework of the Constraine d Minimal Supersymmetric Standard Model.