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

TL;DR

This paper identifies a specific region in the No-Scale F-SU(5) supersymmetric model where LHC top quark reconstruction methods may fail due to soft top quarks, suggesting alternative search strategies for this 'blind spot'.

Contribution

It reveals a new 'blind spot' in LHC SUSY searches for a particular spectral region of the No-Scale F-SU(5) model with TeV-scale vector-like matter.

Findings

Gluino-light stop mass splitting near top quark mass causes soft top quarks.

Standard top reconstruction methods may miss signals in this region.

Alternative search strategies like same sign dileptons are more effective.

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.