https://doi.org/10.1140/epjc/s10052-022-10455-1
Regular Article - Theoretical Physics
Automating scattering amplitudes with chirality flow
Department of Astronomy and Theoretical Physics, Lund University, Box 43, 221 00, Lund, Sweden
Received:
7
April
2022
Accepted:
22
May
2022
Published online:
17
June
2022
Recently we introduced the chirality-flow formalism, a method which builds on the spinor-helicity formalism and is inspired by the color-flow idea in QCD. With this formalism, Feynman rules and diagrams are simplified to the extent that it is often possible to immediately, by hand, write down a helicity amplitude given a Feynman diagram. In this paper we show that the method can also speed up numerical evaluation of scattering amplitudes by considering 
going to n photons in a MadGraph-based tree-level implementation. We find that the computation time is reduced by roughly a factor ten for six photons, and that it scales better with the number of external particles than the default MadGraph5_aMC@NLO implementation. This performance gain is in part attributed to the more compact Lorentz structures involved, and in part due to a transparent choice of gauge reference vectors which reduces the number of Feynman diagrams considered.
© The Author(s) 2022
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