David Curtin, Rouven Essig, Brian Shuve
We use modern jet-substructure techniques to propose LHC searches for multijet-resonance signals without leptons or missing energy. We focus on three-jet resonances produced by R-parity-violating decays of boosted gluinos, showing that shape analyses searching for a mass peak can probe such gluinos up to masses of 750 GeV (650 GeV) with 20/fb (5/fb) at the LHC at 8 TeV. This complements existing search strategies, which also include counting methods that are inherently more prone to systematic uncertainties. Since R-parity-violating gluinos lighter than all squarks hadronize before decaying, we introduce new color-flow variables, "radial pull" and "axis contraction", which are sensitive to the color structure of the R-hadron's decay. The former measures the inward pull of subjets in a fat jet, while the latter quantifies the inward drift of the N-subjettiness axes when changing the distance measure. We show that they can dramatically improve the discrimination of a boosted gluino signal versus QCD, ttbar, and combinatoric background for gluino masses comparable to the top mass. Cuts on axis contraction also noticeably improve the resonance shape for heavy gluinos with masses above 500 GeV. With minor adaptations, these variables could find application in substructure searches for particles in different color representations or with other decay topologies.
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http://arxiv.org/abs/1210.5523
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