Trilepton Signature of Minimal Supergravity at the Upgraded Tevatron

The prospects for detecting trilepton events ($\ell = e$ or $\mu$) from chargino-neutralino ($\chi^\pm_1 \chi^0_2$) associated production are investigated for Run II and Run III at the Fermilab Tevatron Collider in the context of the minimal supergravity model (mSUGRA). In some regions of parameter space, $\chi^\pm_1$ and $\chi^0_2$ decay dominantly into final states with $\tau$ leptons and the contributions from $\tau-$leptonic decays enhance the trilepton signal substantially when soft cuts on lepton transverse momenta are used. The dilepton ($l^+l^-$) invariant mass distribution near the endpoint is considered as a test of mSUGRA mass relations for a case with a large trilepton signal. Additional sources of the mSUGRA trilepton signal are discussed. Discovery contours for $p\bar{p} \to 3\ell +X$ at 2 TeV with an integrated luminosity of 2 fb$^{-1}$ to 30 fb$^{-1}$ are presented in the mSUGRA parameter space of $(m_{1/2},m_0)$ for several choices of $\tan\beta$.