Measurement of Colour Flow with the Jet Pull Angle in tt̅ Events Using the ATLAS Detector a √s̅ = 8 TeV

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 tt̅ 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 √s̅ = 8 TeV at the LHC. The jet pull angle distribution is corrected for detector resolution and acceptance effects and is compared to various models.