Search for New Phenomena in Dijet Angular Distributions in Proton-Proton Collisions at $\sqrt{s} = 8$ TeV Measured with the ATLAS Detector

TL;DR

This paper reports a search for new physics in dijet angular distributions at the LHC using ATLAS data at 8 TeV, finding no deviations from the Standard Model and setting limits on quark compositeness scales.

Contribution

It provides the first constraints on quark contact interactions at 8 TeV using dijet angular distributions with the ATLAS detector.

Findings

No deviations from Standard Model predictions observed.

Excluded quark compositeness scales below 8.1 TeV (destructive interference).

Excluded quark compositeness scales below 12.0 TeV (constructive interference).

Abstract

A search for new phenomena in LHC proton-proton collisions at a center-of-mass energy of $\sqrt{s}=8$ TeV was performed with the ATLAS detector using an integrated luminosity of 17.3 fb$^{-1}$. The angular distributions are studied in events with at least two jets; the highest dijet mass observed is 5.5 TeV. All angular distributions are consistent with the predictions of the Standard Model. In a benchmark model of quark contact interactions, a compositeness scale below 8.1 TeV in a destructive interference scenario and 12.0 TeV in a constructive interference scenario is excluded at 95 % CL; median expected limits are 8.9 TeV for the destructive interference scenario and 14.1 TeV for the constructive interference scenario.