Wherever I see calculations of two-loop contributions to the ##\phi^4## propagator (such as Peskin, page 328, on the bottom), only the sunset diagram (aka the Saturn diagram) is considered, but not, say, the two-loop diagram involving a loop on top of a loop (looks like this: _8_). Does it not contribute? As far as I can tell, it does and the expression for it is(adsbygoogle = window.adsbygoogle || []).push({});

##\int\frac{d^4k}{k^2-m^2}\frac{d^4q}{q^2-m^2}##

with a high degree of divergence (##\Lambda^4##). Am I correct?

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# Phi^4 theory two-loop contributions

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