Search for Long-Lived Charged Massive Particles in $p\overline{p}$ Collisions at $\sqrt{s}=1.8\mathrm{T}\mathrm{e}\mathrm{V}$

We report a search for the production of long-lived charged massive particles in a data sample of $90{\mathrm{p}\mathrm{b}}^{-1}$ of $\sqrt{s}=1.8\mathrm{T}\mathrm{e}\mathrm{V}$ $p\overline{p}$ collisions recorded by the Collider Detector at Fermilab. The search uses the muonlike penetration and anomalously high ionization energy loss signature expected for such a particle to discriminate it from backgrounds. The data are found to agree with background expectations, and cross section limits of $\mathcal{O}(1)$ pb are derived using two reference models, a stable quark and a stable scalar lepton.

Figure 1

$dE/dx$ measurements in control samples are compared to predictions for SVX (open points) and CTC (solid points). The CTC prediction is a fit including detector effects. The SVX prediction is the Bethe-Bloch formula. The agreement is good in the low and high $\beta \gamma$ regions important to this search.

Figure 2

Observed $M_{dE/dx}$ distribution for tracks passing all the cuts for the strong production search in the muon trigger and ${\mathrm{E̸}}_T$ trigger data samples [10]. The curves are the expected background distributions, which have an uncertainty of about 15%, indicated by the gray bands.

Figure 3

Limits set at a 95% confidence level on the production cross section of long-lived fourth generation quarks are compared with the theoretical prediction.