Measurement of colour flow with the jet pull angle in tt¯ events using the ATLAS detector at s=8

Safe use of jet pull

“…We also advocate measuring jet pull in other Standard Model contexts. Measurements of the pull angle have been carried out by the D∅ collaboration at the Tevatron [4] and by the ATLAS collaboration at the LHC [5,6] (in their most recent analysis the ATLAS collaboration also measured the pull magnitude) in events featuring the production of a top and of an antitop. The rich phenomenology of top decay allows for measuring jet pull in a singlet decay by looking, for instance, at the decay of the W boson but also enables one to study more intricate colour correlations, by measuring the pull between one of the b-jets and the incoming beam.…”

“…[3]. Since then, a number of experimental analyses has been devoted to this observable: from a pioneering measurement performed by the D∅ collaboration at the Tevatron [4], to two measurements performed by the ATLAS collaboration at the LHC, at centre-of-mass energy of 8 TeV [5] and 13 TeV [6]. Most of the measurements concentrate in a particular projection of the jet pull vector, the so-called pull angle, that would, in principle offer the best sensitivity.…”

Exclusive physics at the LHC with SuperChic 2

“…As described above, events with proton dissociation may also be considered, but it would also be interesting to examine if jet properties such as the colour flow and multiplicity might be used to isolate the contribution from a colour-singlet initial state, and so investigate these zeros in an inclusive environment. For example, the so-called jet pull angle variable has been shown to be useful in identifying jets which originate from a colour-singlet gg initial state [58,59]. Table 2 Expected number of ggg jet events for which a gluon pairing i j passes cuts on the azimuthal separation φ i j and A i j , defined in the text.…”

Exposing the dead cone effect with jet substructure techniques

“…For example, jet substructure techniques have previously enabled the study of color flow between the final states in top decay [46][47][48], an effect that relies on detecting soft gluons from colorconnected partons.…”