Sorry if this appears a basic question,(adsbygoogle = window.adsbygoogle || []).push({});

but could you pls advise me is it possible to have a two identical vertexes but with different strength coupling?

I have some toy Lagrangian and when I calculate Feynman rules I get for one vertex following expression:

(M1+M2)*(combination of fields )+M1(combination of fields).

Where M1 and M2 are coupling strength, so if I want to calculate some process in some order I should consider diagrams of the same order with respect to the coupling strenght. And in my case I am calculating diagrams with respect to M2 strength coupling.... so does it mean that for my vertex I should extract only M2 coupling part from that general vertex which wrote above: (M1+M2)*(combination of fields ) - > (M2)*(combination of fields ) ?

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# Coupling order in Fenman diagrams

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