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.

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# LSZ formula help!

**Physics Forums | Science Articles, Homework Help, Discussion**