• is a subtraction scheme that will work at N³LO [Engel, Signer, Ulrich 2019]
• ‘just’ need the matrix elements 😁
• impossible in most cases, plausible for
  • VVV: HQFF, known [Fael, Lange, Schönwald, Steinhauser 2022] [Egner, Fael, Lange, Schönwald, Steinhauser 2022] [Fael, Lange, Schönwald, Steinhauser 2022] [Fael, Lange, Schönwald, Steinhauser 2023]
  • RVV: known for massless electrons from the Turin group as (talk on Thursday by Ryan Moodie)
  • RRV: OpenLoops [[Buccioni:2017yxi] [Buccioni, Lang, Lindert, Maierhöfer, Pozzorini, Zhang, Zoller 2019]
  • RRR: ‘trivial’