The WIMP limit from an accelerator experiment

Searches for pair production of sfermions and charginos and associated production of neutralinos have been performed using the data collected by the ALEPH detector at centre-of-mass energies ranging from 188.6 to 201.6 GeV. No evidence for any such signals is observed in a total of about 410 pb/sup -1/ accumulated luminosity. The negative results of such searches are translated into exclusion domains in the space of the relevant Minimal Supersymmetric Model parameters, improving significantly on the previous constraints. Under the assumptions of gaugino and sfermion mass unification, these results allow a 95% confidence level lower limit of 36.8 GeV/c/sup 2/ to be set on the mass of the lightest supersymmetric particle, for any tan P and sfermion mass. Additional constraints in the MSSM parameter space have been derived including the negative results of ALEPH searches for Higgs bosons. These raise the above limit to 38 Ge V/c/sup 2/. (6 refs).