Search for Gluino-Mediated Bottom Squark Production in $p\overline{p}$ Collisions at $\sqrt{s}=1.96\mathrm{TeV}$

We report on a search for the supersymmetric partner of the bottom quark produced from gluino decays in data from $2.5{\mathrm{fb}}^{-1}$ of integrated luminosity collected by the Collider Detector at Fermilab at $\sqrt{s}=1.96\mathrm{TeV}$. Candidate events are selected requiring two or more jets and large missing transverse energy. At least two of the jets are required to be tagged as originating from a $b$ quark to enhance the sensitivity. The results are in good agreement with the prediction of the standard model processes, giving no evidence for gluino decay to bottom squarks. This result constrains the gluino-pair-production cross section to be less than 40 fb at 95% credibility level for a gluino mass of $350\mathrm{GeV}/c^2$.

Figure 1

Distribution of ${\mathrm{E̸}}_T$ in the preoptimization region in which leading $E_T$ and second-leading $E_T$ jets are not aligned with the ${\mathrm{E̸}}_T$, and isolated leptons are vetoed. SM prediction (stacked histograms) and observed distribution (dots) are shown, where HF multijets and light-flavor jets are predicted from data as an integrated estimation.

Figure 2

Observed (solid lines) and expected (dashed lines) 95% C.L. upper limit on the gluino cross section (solid line with band) as a function of the gluino mass for two assumed values of the sbottom mass. The shaded band denotes the uncertainty on the NLO $\tilde{g}\tilde{g}$ production due to the truncated higher-order terms and the parton distribution functions.

Figure 3

Excluded region at 95% C.L. in the $m(\tilde{g})\mathrm{\text{−}}m(\tilde{b})$ plane for a $m({\tilde{\chi }}^0)=60\mathrm{GeV}/c^2$, $m(\tilde{q})=500\mathrm{GeV}/c^2$. The result is compared to the previous results from CDF in run I [8], and run II [9] and direct sbottom production by D0 [7].