Comments on a new `full colour' parton shower

Understand

A new parton shower algorithm has been presented with the claim of providing soft-gluon resummation at `full colour' (arXiv:2001.11492).

• In this paper we show that the algorithm does not succeed in this goal.
• We show that full colour accuracy requires the Sudakov factors to be defined at amplitude level and that the simple parton-shower unitarity argument employed in arXiv:2001.11492 is not sufficient.