Improving colour computations in MadGraph5_aMC@NLO and exploring a 1 / N_c expansion

Summary, in English

In this paper, we present an extension of MadGraph5_aMC@NLO which is able to evaluate tree-level QCD matrix-elements up to 2 → 6 (one more particle than before). To achieve this, we implemented Berends–Giele-like recursion, and re-implemented the way colour is computed such that we can now expand the colour matrix in powers of 1 / N_c and truncate this expansion to a chosen order. For high multiplicity samples, even without truncating the colour matrix, the new implementation offers a speed gain compared to the previous MadGraph5_aMC@NLO code.

• Author: Andrew Lifson; Olivier Mattelaer
• Department/s: Theoretical Particle Physics - Has been reorganised
• Publishing year: 2022-12
• Language: English
• Publication/Series: European Physical Journal C
• Volume: 82
• Issue: 12
• Links: http://dx.doi.org/10.1140/epjc/s10052-022-11078-2
• Document type: Journal article
• Publisher: Springer
• Topic: Subatomic Physics
• Status: Published
• Project: The Chirality-Flow Formalism and Optimising Scattering Amplitudes
• ISBN/ISSN/Other: ISSN: 1434-6044