Search for Pair Production of Scalar Top Quarks in $R$-Parity Violating Decay Modes in $p\overline{p}$ Collisions at $\sqrt{s}=1.8\mathrm{T}\mathrm{e}\mathrm{V}$

We present the results of a search for pair production of scalar top quarks (${\tilde{t}}_1$) in an $R$-parity violating supersymmetry scenario in $106{\mathrm{p}\mathrm{b}}^{-1}$ of $p\overline{p}$ collisions at $\sqrt{s}=1.8\mathrm{T}\mathrm{e}\mathrm{V}$ collected by the Collider Detector at Fermilab. In this mode each ${\tilde{t}}_1$ decays into a $\tau$ lepton and a $b$ quark. We search for events with two $\tau$’s, one decaying leptonically ($e$ or $\mu$) and one decaying hadronically, and two jets. No candidate events pass our final selection criteria. We set a 95% confidence level lower limit on the ${\tilde{t}}_1$ mass at $122\mathrm{G}\mathrm{e}\mathrm{V}/c^2$ for $\mathrm{B}\mathrm{r}({\tilde{t}}_1\to \tau b)=1$.

Figure 1

The final data selection criteria for the $\mathrm{O}\mathrm{S}\ell {\tau }_h+\ge 2$ jet sample. The arrows show the final event selection requirements.

Figure 2

The number of charged tracks in each ${\tau }_h$ candidate for the opposite-sign (OS) $\ell {\tau }_h+0$ jet control sample. The data are compared to the MC expectation (all backgrounds are summed) which is dominated by real ${\tau }_h$’s from $Z\to {\tau }^{+}{\tau }^{-}$ production.

Figure 3

The 95% C.L. upper limit on cross section times Br for ${\tilde{t}}_1{\overline{\tilde{t}}}_1$ production compared to the NLO calculations.