Quantum Field Theory and the Standard Model by Schwartz M.D. z-lib.org · Problem 7.2

Feynman rules — Schwartz M.D. z-lib.org

Physics — QFT · disconnected-diagrams-interference

Problem

Calculate the contribution to

2 \to 4

scattering from the Lagrangian

\mathcal{L} = -\frac{1}{2}\phi\Box\phi + \frac{g}{3!}\phi^3 + \frac{1}{6!}\lambda\phi^6

from both the connected diagram, with the 6-point vertex, and the disconnected diagram with the 3-point vertex. Show that there is no interference between the two diagrams. (There are of course many connected diagrams with the 3-point vertex that you can ignore.)

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