Paper: https://arxiv.org/pdf/2004.13788 standard helicity formalism <img width="1035" alt="image" src="https://github.com/user-attachments/assets/b4077f22-bb81-44f8-b082-52c7f5a49a41"> should be easy to code starting point: https://gist.github.com/mmikhasenko/5d8772ba1dd8d5cb3e35515299c3456f
Paper: https://arxiv.org/pdf/2004.13788
standard helicity formalism
starting point: https://gist.github.com/mmikhasenko/5d8772ba1dd8d5cb3e35515299c3456f