Search for Pair Production of Supersymmetric Top Quarks in Dilepton Events from $p\bar{p}$ Collisions at $\sqrt{s}$ = 1.96 TeV

Abstract

We present the results of a 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 $\chargino$ with a subsequent $\chargino$ decay into a neutralino $\neutralino$, lepton $\ell$, and neutrino $\hat{I}½$. Using a data sample corresponding to 2.7 fb${}^{-1}$ of integrated luminosity of $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV collected by the CDF II detector, we reconstruct the mass of candidate stop events and fit the observed mass spectrum to a combination of standard model processes and stop quark signal. We find no evidence for $\pairstop$ production and set 95% C.L. limits on the masses of the stop quark and the neutralino for several values of the chargino mass and the branching ratio ${\cal B}(\chargino\to\neutralino\ell^{\pm}ν)$.

Accepted to Phys. Rev. Lett