t(t)over-bart(t)over-bar signatures through the lens of color-octet scalars

We reinterpret two recent LHC searches for events containing four top quarks (t (t) over bart (t) over bar) in the context of supersymmetric models with Dirac gauginos and color-octet scalars (sgluons). We explore whether sgluon contributions to the four-top production cross section sigma-(pp -> t (t) over bart (t) over bar) can accommodate an excess of four-top events recently reported by the ATLAS collaboration. We also study constraints on these models from an ATLAS search for new phenomena with high jet multiplicity and significant missing transverse energy (E-T(miss)) sensitive to signals with four top quarks. We find that these two analyses provide complementary constraints, with the jets + E-T(miss) search exceeding the four-top cross section measurement in sensitivity for sgluons heavier than about 800 GeV. We ultimately find that either a scalar or a pseudoscalar sgluon can currently fit the ATLAS excess in a range of reasonable benchmark scenarios, though a pseudoscalar in minimal Dirac gaugino models is ruled out. We finally offer sensitivity projections for these analyses at the HL-LHC, mapping the 5 sigma discovery potential in sgluon parameter space and computing exclusion limits at 95% CL in scenarios where no excess is found.

Automated summary

The study reinterprets two recent LHC searches, explores the possibility of sgluon contributing to an excess of four-top events, and investigates constraints on these models. The results indicate that the jets + E-T(miss) search exceeds the sensitivity of the four-top cross section measurement for sgluons.