Searches for R--Parity Violating Decays of Scalar Fermions at LEP              
  
A search for pair produced scalar fermions with couplings                      
that violate R-parity  has been performed                                      
using a data sample corresponding to an integrated luminosity of               
56 pb^-1 at a centre-of-mass energy of sqrt{s}= 183 GeV                        
collected with the OPAL detector at LEP.                                       
Searches for R-parity violating decays of charged sleptons,                    
sneutrinos and stop quarks 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.                                                              
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.                      
  
 Parallel session :11                  
 Plenary  session :7a