Search for top squarks at the Fermilab Tevatron collider.

Abstract

The lighter superpartner of the top quark ($\tt_1$) may be considerably lighter than squarks of the first two generations, and hence may be accessible to Tevatron collider searches, even if the other squarks and the gluino are too heavy. For the range of $m_{\tt_1}$ of interest at the Tevatron, the $\tt_1$ decays to a chargino via $\tt_1 \to b\tw_1$ if this is kinematically allowed; otherwise, the flavor-changing loop decay $\tt_1 \to c\tz_1$ dominates. In the latter case, $\tt_1$ production is signalled by jet(s) plus $\eslt$ events. If, instead, the chargino decay is allowed, $1\ell + b$-$jets + \eslt$ and $\ell^+\ell'^- + jet(s) + \eslt$ events from leptonic decays of $\tw_1$ provide the most promising signals. We perform detailed simulations for each of these signals using ISAJET 7.07 and devise cuts to enable the extraction of each of these signals above standard model backgrounds from vector boson or top quark production. With an integrated luminosity of 100 $pb^{-1}$, experiments should be able to probe top squark masses up to $\sim 100$ GeV in each of these channels; the detection of the signal in the single lepton channel, however, requires reasonable capability to tag displaced $b$ decay vertices in the central region.