A search for dijet resonances in the mass range of 100-250 GeV is presented using proton-proton collision data recorded by the ATLAS experiment at the Large Hadron Collider at a centre-of-mass energy of 13 TeV. Conventional searches for hadronic resonances in the sub-TeV regime are heavily constrained by high jet trigger thresholds required to manage the overwhelming rate of Standard Model multijet background processes described by quantum chromodynamics. To overcome this limitation, this analysis uses a novel strategy that separately reconstructs multiple proton-proton interactions per bunch crossing, known as pile-up collisions. The dataset was collected by the ATLAS experiment using single-electron and single-muon triggers in 2016-2018 corresponding to an integrated luminosity of 1. 30 pb^-1, which represents the effective luminosity of pile-up collisions recorded alongside triggered events. This constitutes the first application of pile-up collisions to probe low dijet mass scales. No significant excess is observed above the background expectation and exclusion limits are set for a generic Gaussian model and a simplified dark matter model featuring an axial-vector mediator with coupling to quarks.
Aad et al. (Thu,) studied this question.