Search for a Dark Matter Candidate Produced in Association with a Single Top Quark in $p\overline{p}$ Collisions at $\sqrt{s}=1.96\mathrm{TeV}$

We report a new search for dark matter in a data sample of an integrated luminosity of $7.7{\mathrm{fb}}^{-1}$ of Tevatron $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$, collected by the CDF II detector. We search for production of a dark-matter candidate, $D$, in association with a single top quark. We consider the hadronic decay mode of the top quark exclusively, yielding a final state of three jets with missing transverse energy. The data are consistent with the standard model; we thus set 95% confidence level upper limits on the cross section of the process $p\overline{p}\to t+D$ as a function of the mass of the dark-matter candidate. The limits are approximately 0.5 pb for a dark-matter particle with mass in the range of $0–150\mathrm{GeV}/c^2$.

Figure 1

The ${\mathrm{E̸}}_T$ distribution in a control region requiring an identified high-$p_T$ lepton; the gray area represents the statistical and systematic uncertainties on the background model. The lower panel displays the difference between the data and the expected backgrounds (Exp) divided by the latter.

Figure 2

The ${\mathrm{E̸}}_T$ distribution in the signal region. The data are compared to the sum of the SM contributions. The distribution of signal events with a DM mass of $125\mathrm{GeV}/c^2$ is also shown.

Figure 3

Exclusion curve of the monotopic cross section as a function of the mass of DM particle.