Abstract
This Letter presents the results of a search for pair-produced particles of masses above 100GeV that each decay into at least four quarks. Using data collected by the CMS experiment at the LHC in 2015-2016, corresponding to an integrated luminosity of 38.2 fb^{-1}, reconstructed particles are clustered into two large jets of similar mass, each consistent with four-parton substructure. No statistically significant excess of data over the background prediction is observed in the distribution of average jet mass. Pair-produced squarks with dominant hadronic R-parity-violating decays into four quarks and with masses between 0.10 and 0.72TeV are excluded at 95%confidence level. Similarly, pair-produced gluinos that decay into five quarks are also excluded with masses between 0.10 and 1.41TeV at 95%confidence level. These are the first constraints that have been placed on pair-produced particles with masses below 400GeV that decay into four or five quarks, bridging a significant gap in the coverage of R-parity-violating supersymmetry parameter space.
Highlights
Despite the many successes of the CERN LHC program, a solution to the hierarchy problem [1,2], which arises from the large difference between the electroweak and Planck scales, remains elusive
We take advantage of the large cross section predicted for squark pair production, focusing on the small fraction of phase space in which the squarks are produced back to back and the decay products of each squark reside entirely within a single large jet
The tt events in control regions are used in the estimation of the selection efficiency, jet mass scale, and jet mass resolution. The motivation for this search comes from natural SUSY, but the analysis aims more broadly for new phenomena in general
Summary
While Rparity-conserving models of SUSY [14] have been emphasized because they can parsimoniously accommodate a dark matter candidate, R-parity-violating (RPV) models still lack constraints in a number of important scenarios [15,16] This analysis probes a previously unexamined region of the SUSY model space, where pair-produced squarks with masses as light as 100 GeV each decay into four nontop quarks through hadronic RPV couplings [17]. This refinement serves to suppress perturbative radiation characteristic of QCD multijet events as well as to reduce the contribution to jet masses from detector noise, pileup, and the underlying event. We study a variety of alternative choices of CR fat-jet tags, which
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