Search for massive particles producing all hadronic final states in proton-proton collisions at the LHC with the ATLAS detector

A search for massive particles giving rise to all hadronic decays to many jets is presented. The analysis selects events that pass a trigger based on the total and leading jet transverse momentum. A data sample of √s = 13 TeV proton-proton collisions collected by the ATLAS detector between 2015 and 2018, corresponding to a total integrated luminosity of 140 fb−1 , is used for this search. The analysis deploys two techniques – a traditional method that searches for an excess number of jets above a transverse momentum threshold and a new first of it’s kind machine learning based mass resonance search. The standard model background is estimated for the jet counting method using data with scale factors derived from simulations, while that of the mass resonance method is entirely derived from data. A simplified R-parity-violating supersymmetric model is considered with a baryon number violating coupling λ′′ . The observed yields are compatible with those expected from background processes. Results are presented as limits at 95% confidence level on the model-independent cross section and interpreted as exclusion limits on scenarios with pair-production of prompt gluinos that decay via λ′′ to six (direct) or ten (cascade) quarks in total. Gluinos with masses up to 1.8 and 2.2 TeV are excluded for the direct and cascade decay models, respectively.