Supersymmetry reach of Fermilab Tevatron upgrades: The largetanβcase

The Yukawa couplings of the tau lepton and the bottom quark become comparable to, or even exceed, electroweak gauge couplings for large values of the supersymmetry parameter $\tan \beta .$ As a result, the lightest tau slepton ${\tilde{\tau }}_1$ and bottom squark $b_1$ can be significantly lighter than corresponding sleptons and squarks of the first two generations. Gluino, chargino, and neutralino decays to third generation particles are significantly enhanced when $\tan \beta$ is large. This affects projections for collider experiment reach for supersymmetric particles. In this paper, we evaluate the reach of the Fermilab Tevatron $p\overline{p}$ collider for supersymmetric signals in the framework of the minimal supergravity model. We find that the reach via signatures with multiple isolated leptons (e and μ) is considerably reduced. For very large $\tan \beta ,$ the greatest reach is attained in the $\mathrm{multijet}{+E}_T^{\mathrm{miss}}$ signature. Some significant extra regions may be probed by requiring the presence of an identified b jet in $\mathrm{jets}{+E}_T^{\mathrm{miss}}$ events, or by requiring one of the identified leptons in clean trilepton events to actually be a hadronic 1 or 3 charged prong tau. In an appendix, we present formulas for chargino, neutralino, and gluino three body decays which are valid at large $\tan \beta .$