Constricted SUSY from No-Scale F-SU(5): A "Blind Spot" for LHC Top Quark Reconstruction?

Abstract

We describe a region of the No-Scale F-SU(5) supersymmetric model with TeV-scale vector-like matter multiplets that is potentially opaque to LHC observations based upon top quark reconstruction. Possessing a 100% on-shell branching fraction for gluino to light stop decays, the gluino-light stop mass splitting in F-SU(5) lies very close to the top quark rest mass in the region 810 (650) <~ M(gluino) (M(light stop)) <~ 1170 (975) GeV. For unboosted gluino pair-production, this could render two soft top quarks in the dominant 4-top signature, greatly reducing the likelihood for discrimination from the combinatoric background. We therefore suggest that caution is warranted when gluino exclusion bounds on models possessing a similar spectral character (gluino heavier than the light stop but lighter than all other squarks) using multijet SUSY search tactics. Alternate search methods are highlighted, including those based upon same sign dileptons and multiple heavy flavor tags, which are more sensitive to this delicate kinematic "blind spot" crease.