Trileptons from the top quark

The cascade decays of $t\bar{t}$, $t\bar{b}$, $b\bar{t}$, and $b\bar{b}$ systems produced in $p\bar{p}$ collisions by strong or electroweak mechanisms lead to trilepton events, which offer top-quark signatures free from $c\bar{c}$ and Drell-Yan backgrounds. Even a few events could be valuable. Since at least two of the leptons must have a common parent, same-sign trileptons or events with opposite-sign pair masses greater than $m_b$ must have top origins, and the minimum pair invariant mass in such events gives a lower bound on the top mass. Alternative $t\bar{t}$ and $t\bar{b}\left(b\bar{t}\right)$ origins can be distinguished by topology and/or lepton isolation.