Early supersymmetry discovery at the CERN LHC without missingET: The role of multileptons

Abstract

Traditional searches for supersymmetry (SUSY) at hadron colliders rely heavily on the presence of large missing transverse energy ($M{E}_{T}$) to reject background compared to signal. On the other hand, initial searches for new physics at the CERN LHC may not be able to rely on $M{E}_{T}$ due to a variety of detector calibration issues. We show that much of SUSY parameter space is accessible to discovery even without using $M{E}_{T}$, and with rather low integrated luminosities, $0.1--1\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$. A key role is played by isolated lepton multiplicity which arises from gluino and squark cascade decays. Requiring $\ensuremath{\ge}3$ isolated leptons plus jets yields a high rate of background rejection compared to signal. We find an LHC reach in ${m}_{\stackrel{\texttildelow{}}{g}}$ of about 700--750 GeV for just $0.1\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of integrated luminosity by requiring events with $\ensuremath{\ge}4$ jets plus $\ensuremath{\ge}3$ isolated leptons but without using $M{E}_{T}$. If a large enough event sample is assembled, then kinematic reconstruction of sparticle mass properties should be possible just as in the case where large missing ${E}_{T}$ is required. SUSY without $M{E}_{T}$ can also be seen in opposite-sign/same flavor dilepton plus jets events when a characteristic invariant mass edge stands out against background.