Search for Pair Production of Supersymmetric Top Quarks in Dilepton Events at the Tevatron

We search for pair production of the supersymmetric partner of the top quark, the stop quark (tilde t)1, decaying to a b-quark and a chargino (tilde χ)1± with a subsequent decay into a neutralino (tilde χ)10, lepton (ell), and neutrino ν. Using 2.7 fb-1 of √s = 1.96 TeV p(bar p) collision data collected by the CDF II experiment, we reconstruct the mass of candidate stop events and fit the observed mass spectrum to a combination of standard model processes and stop signal. No evidence of (tilde t)1(tilde (bar 1))1 production is found, therefore we set 95% C.L. limits on the masses of the stop and the neutralino for several values of the chargino mass and the branching ratio Β ((tilde χ)1± → (tilde χ)10(ell)±ν).