Measurement of colour flow with the jet pull angle in $t\bar{t}$ events using the ATLAS detector at $\sqrt{s}=8$ TeV

TL;DR

This paper measures the jet pull angle in top-antitop events to study colour flow between quarks and gluons, providing insights into QCD predictions and jet substructure modeling.

Contribution

It presents the first measurement of the jet pull angle in $t\bar{t}$ events at 8 TeV, comparing data to various theoretical models.

Findings

Jet pull angle distribution agrees with some models within uncertainties.

Results provide constraints on colour flow modeling in top quark events.

Measurement techniques improve understanding of jet substructure and QCD dynamics.

Abstract

The distribution and orientation of energy inside jets is predicted to be an experimental handle on colour connections between the hard--scatter quarks and gluons initiating the jets. This Letter presents a measurement of the distribution of one such variable, the jet pull angle. The pull angle is measured for jets produced in $t\bar{t}$ events with one $W$ boson decaying leptonically and the other decaying to jets using 20.3 fb$^{-1}$ of data recorded with the ATLAS detector at a centre-of-mass energy of $\sqrt{s}=8$ TeV at the LHC. The jet pull angle distribution is corrected for detector resolution and acceptance effects and is compared to various models.