Search for Long-lived Charged Massive Particles at CDF

TL;DR

This study searches for long-lived charged massive particles (CHAMPs) in 90 pb$^{-1}$ of CDF Run1B data, using two reference models: a strongly produced stable color-triplet quark and a weakly produced long-lived slepton in Gauge Mediated SUSY Breaking (GMSB). CHAMPs are identified via highly ionizing tracks with low $\beta\gamma$, measured through $dE/dx$ in the CTC and SVX, with trigger-assisted selection and cuts on $\beta\gamma$ and $M_{SVX}$. No excess over background is observed; the analysis sets mass limits on heavy stable quarks ($M>195$ GeV/$c^2$ for $q=1/3$ and $M>220$ GeV/$c^2$ for $q=2/3$) and a slepton cross-section limit of $\sigma_{95\%}\approx 550$ fb, though the slepton limit remains well above the predicted rate. RunII prospects anticipate ~20x more luminosity and detector enhancements, including Time-of-Flight, to extend sensitivity to CHAMP production in GMSB scenarios and improve background rejection.

Abstract

A search for long-lived charged massive particles in CDF's Run1b data sample is presented. The search looks for highly ionizing tracks which would result from slowly moving massive particles. We search for strongly produced particles using a stable color triplet quark as a reference model, and a separate search was performed for weakly produced particles using long-lived sleptons in Gauge Mediated Supersymmetry Breaking as a reference model. No excess over background was observed, and we derive limits on the cross-sections for production of these particles. Prospects for RunII are also discussed.

Figures (4)

• Figure 1: Observed M$_{SVX}$ distribution for tracks passing all the cuts for the strong search in the muon triggered data sample. The solid curves are the expected background distributions.
• Figure 2: Observed M$_{SVX}$ distribution for tracks passing all the cuts for the strong search in the $E_{T}\space/\space$ triggered data sample. The solid curve is the distribution of the 63 $\pm$ 9 expected background events.
• Figure 3: Limits on heavy stable quarks derived from results of the strong search.
• Figure 4: Limits on long-lived Drell-Yan sleptons derived from results of the strong search.