Measurements of top-quark pair single- and double-differential cross-sections in the all-hadronic channel in $pp$ collisions at $\sqrt{s}=13~\mbox{TeV}$ using the ATLAS detector

TL;DR

This paper reports detailed measurements of top-quark pair production cross-sections in the all-hadronic decay channel at 13 TeV using ATLAS data, revealing areas where theoretical models do not match observed data.

Contribution

It provides the first comprehensive measurement of single- and double-differential cross-sections for top-quark pairs in the all-hadronic channel at 13 TeV, including correlations with additional jet radiation.

Findings

Modelled rapidities match data well

Transverse momenta of leading jets are mismodeled

Top-quark and pair transverse momenta are incompatible with predictions

Abstract

Differential cross-sections are measured for top-quark pair production in the all-hadronic decay mode, using proton$-$proton collision events collected by the ATLAS experiment in which all six decay jets are separately resolved. Absolute and normalised single- and double-differential cross-sections are measured at particle and parton level as a function of various kinematic variables. Emphasis is placed on well-measured observables in fully reconstructed final states, as well as on the study of correlations between the top-quark pair system and additional jet radiation identified in the event. The study is performed using data from proton$-$proton collisions at $\sqrt{s}=13~\mbox{TeV}$ collected by the ATLAS detector at CERN's Large Hadron Collider in 2015 and 2016, corresponding to an integrated luminosity of $\mbox{36.1 fb}^{-1}$. The rapidities of the individual top quarks and of the top-quark pair are well modelled by several independent event generators. Significant mismodelling is observed in the transverse momenta of the leading three jet emissions, while the leading top-quark transverse momentum and top-quark pair transverse momentum are both found to be incompatible with several theoretical predictions.