Search for Pair Production of Supersymmetric Top Quarks in Dilepton Events from pp Collisions at √(s)=1.96 TeV

We present the results of a search for pair production of the supersymmetric partner of the top quark (the top squark t-tilde1) decaying to a b quark and a chargino χ-tilde1± with a subsequent χ-tilde1± decay into a neutralino χ-tilde10, lepton l, and neutrino ν. Using a data sample corresponding to 2.7 fb-1 of integrated luminosity of pp collisions at √(s)=1.96 TeV collected by the CDF II detector, we reconstruct the mass of top squark candidate events and fit the observed mass spectrum to a combination of standard model processes and t-tilde1t-tilde1 signal. We find no evidence for t-tilde1t-tilde1 production and set 95% C.L. limits on the masses of the top squark and the neutralino for several values of the chargino mass and the branching ratio B(χ-tilde1±→χ-tilde10l±ν).