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 $ν$. 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 ${\cal B}(\chargino\to\neutralino\ell^{\pm}ν)$.

Figures (2)

• Figure 1: The reconstructed $\tilde{t}_{1}$ mass distribution. The dashed line represents an example of the $\tilde{t}_{1}\bar{\tilde{t}}_{1}$ signal distribution.
• Figure 2: The observed 95% C.L. exclusion regions in the $m_{\tilde{\chi}_{1}^{0}}$ and $m_{\tilde{t}_1}$ mass plane for several values of ${\cal B}$($\tilde{\chi}_{1}^{\pm}\rightarrow\tilde{\chi}_{1}^{0}\ell^{\pm}\nu$) and $m_{\tilde{\chi}_{1}^{\pm}}$. The excluded region corresponds to the area below the lines. Universality of $e$, $\mu$, and $\tau$ in the $\tilde{\chi}_{1}^{\pm}$ decays is assumed.