Top pair production with an extra gluon at the Tevatron

We calculate top pair production and decay at the Tevatron $p\bar p$ collider, with the emission of an extra gluon, and study the corresponding $W+5$\,jet top signals including full spin correlations in the $W \to \ell\nu$ leptonic and $W\to jj$ hadronic decays. We study the feasibility of reconstructing $W+5$\,jet top events with a single $b$-tag, including realistic energy resolution. Our suggested basic procedure based on kinematic fitting achieves about 74\% reconstruction efficiency, with 74\% of the reconstructed events correctly classified (purity); this improves to 82\% efficiency with 77\% purity in double-$b$-tagged events. We suggest possible refinements, based on virtuality criteria, that give higher purity at the cost of lower reconstruction efficiency.