Measurements of jet cross-section ratios in 13 TeV proton--proton collisions with ATLAS

TL;DR

This paper presents detailed measurements of jet cross-section ratios in 13 TeV proton-proton collisions, providing sensitive tests of quantum chromodynamics and the strong coupling constant with reduced systematic uncertainties.

Contribution

It introduces new measurements of jet multiplicity ratios and related observables that are sensitive to the strong coupling and are less affected by systematic uncertainties.

Findings

Measured jet cross-section ratios with high precision.

Compared measurements with advanced QCD predictions including NNLO.

Achieved reduced jet energy scale uncertainties.

Abstract

Measurements of jet cross-section ratios between inclusive bins of jet multiplicity are performed in 140 fb$^{-1}$ of proton--proton collisions with $\sqrt{s}=13$ TeV center-of-mass energy, recorded with the ATLAS detector at CERN's Large Hadron Collider. Observables that are sensitive the energy-scale and angular distribution of radiation due to the strong interaction in the final state are measured double-differentially, in bins of jet multiplicity, and are unfolded to account for acceptance and detector-related effects. Additionally, the scalar sum of the two leading jets' transverse momenta is measured triple-differentially, in bins of the third jet's transverse momentum as well as bins of jet multiplicity. The measured distributions are used to construct ratios of the inclusive jet-multiplicity bins, which have been shown to be sensitive to the strong coupling $\alpha_{\textrm S}$ while being less sensitive than other observables to systematic uncertainties and parton distribution functions. The measured distributions are compared with state-of-the-art QCD calculations, including next-to-next-to-leading-order predictions. Studies leading to reduced jet energy scale uncertainties significantly improve the precision of this work, and are documented herein.