How to calculate Feynman diagrams in phi^4

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1. Nov 24, 2015

Higgsy

For quartic scalar field theory these are some of the lowest order diagrams (taken from the solutions to 9.2 srednicki). I'm wondering if someone can give me an intuition of how to actually calculate them.

What I'm thinking is that vertices are $$\int \frac{d^{4}x}{(2\pi)^{4}}$$ and for the first diagram their would be two contractions $$\Delta (0)$$ because the propagators return to the place they originated at. So would the first diagram just be $$\Delta (0) ^{2} \int \frac{d^{4}x}{(2\pi)^{4}}$$

Self-studying is incredibly difficult! Any help would be much appreciated! :)

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2. Nov 24, 2015