Search for New Phenomena in Dijet Events with the ATLAS Detector at $\sqrt{s}$=13 TeV with 2015 and 2016 data

This note discusses a search for new physics in events with a pair of jets (dijets) produced in proton-proton collisions in the LHC at a centre-of-mass energy of $\sqrt{s}=13$ TeV. Mass and angular distributions of dijet events are studied with the ATLAS detector using the data collected in 2015 and 2016, corresponding to an integrated luminosity of 3.5 $fb^{-1}$ and 12.2 $fb^{-1}$, respectively. No significant deviations from the Standard Model predictions are observed in angular distributions; no significant local excesses are seen in the dijet mass distribution. Exclusion limits are set at 95% CL on a selection of benchmark models and on generic resonant signals. Excited quarks below 5.6 TeV, heavy $W$ bosons below 2.9 TeV, excited $W$ bosons below 3.3 TeV, and quantum black holes with six extra space-time dimensions for quantum gravity scales below 8.7 TeV are excluded. Limits are also set on heavy $Z$ bosons for a range of boson masses and quark couplings in a dark matter mediator model. Non-resonant new physics contributions from contact interaction models are excluded for characteristic scales $\Lambda$ below 19.9 TeV and 12.6 TeV for constructive and destructive interference with QCD respectively.