I need some help getting started with calculating a two to two scattering amplitude (tree approximation) in the field theory with lagrangian:(adsbygoogle = window.adsbygoogle || []).push({});

g[tex]^{2}[/tex]L = ([tex]\partial[/tex][tex]\phi[/tex])[tex]^{2}[/tex] - V([tex]\phi[/tex])

where V is a polynomial in [tex]\phi[/tex]. That is,

V = [tex]\Sigma[/tex]v[tex]_{n}[/tex][tex]\phi^{n}[/tex]

I am trying to calculate this using techniques of path integration and the lsz formula. I know the answer depends only on v[tex]_{2}[/tex], v[tex]_{3}[/tex], and v[tex]_{4}[/tex] but I don't understand why. When I tried calculating the 4-point green's function I got it depending only on v[tex]_{4}[/tex] so I must be doing something wrong, but I don't know what.

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# LSZ formula help!

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