Search for New Phenomena in Dijet Mass and Angular Distributions with the ATLAS Detector at √s = 13 TeV

This note describes a search for pairs of jets (dijets) produced by phenomena beyond the Standard Model in 80/pb of proton-proton collisions with a centre-of-mass energy of $\sqrt{s}=13$ TeV recorded by the ATLAS detector at the Large Hadron Collider. We examine the distribution of the invariant mass of the two leading jets for local excesses atop a data-driven estimate of the smoothly-falling distribution predicted by the Standard Model. We also compare the data to a Monte Carlo simulation of the Standard Model using the distribution of an angular variable, $\chi$, derived from the rapidity of the two jets. Both distributions lack evidence for anomalous phenomena. We exclude Quantum Black Holes with masses below 6.8 TeV or 6.5 TeV in two benchmark scenarios. We also set 95% C.L. upper limits on the cross section for new processes that would produce a Gaussian contribution to the dijet mass distribution. We exclude Gaussian contributions with effective cross sections ranging from approximately 0.4--2 pb below 2 TeV to 0.05--0.09 pb above 4 TeV.