Regular Article - Theoretical Physics
Improvements on dipole shower colour
Consortium for Fundamental Physics, School of Physics & Astronomy, University of Manchester, M13 9PL, Manchester, United Kingdom
2 Particle Physics, Faculty of Physics, University of Vienna, 1090, Wien, Austria
Accepted: 14 April 2021
Published online: 27 April 2021
The dipole formalism provides a powerful framework from which parton showers can be constructed. In a recent paper (Forshaw et al. 2020), we proposed a dipole shower with improved colour accuracy and in this paper we show how it can be further improved. After an explicit check at we confirm that our original shower performs as it was designed to, i.e. inheriting its handling of angular-ordered radiation from a coherent branching algorithm. We also show how other dipole shower algorithms fail to achieve this. Nevertheless, there is an topology where it differs at sub-leading from a coherent branching algorithm. This erroneous topology can contribute a leading logarithm to some observables and corresponds to emissions that are ordered in but not angle. We propose a simple, computationally efficient way to correct this and assign colour factors in accordance with the coherence properties of QCD to all orders in .
© The Author(s) 2021
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