I have a very trivial question to ask and it would be great if someone could(adsbygoogle = window.adsbygoogle || []).push({});

help me in this.

The statement that '3-point amplitudes' and the location of poles are sufficient to

determine any n-point amplitude at tree level is confusing to me. Don't I also need to know

4-point amlitudes, for example in YM theory ? The reason I say this is

the 4-point vertex can not be broken down. That is the residues obtained upon putting

propagators onshell will also contain 4-point functions.

What am I missing ?

Thanks for your help in advance.

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# Scattering Amplitudes BCFW relation (A question)

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