How to Count Wick Contractions in Phi^3 Theory?

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SUMMARY

The discussion focuses on calculating the time-ordered product T(:\phi^{3}(x)::\phi^{3}(y):) in phi^{3} theory. The user successfully counted the first-order Wick contractions as 9 and second-order as 12, but expressed uncertainty regarding the accuracy of these counts and the third-order contractions. The final expression includes terms involving the Feynman propagator, \Delta_{F}(x-y), and the user deduced that the coefficient A for the third-order term is 6.

PREREQUISITES
  • Understanding of Wick's theorem in quantum field theory
  • Familiarity with phi^{3} theory
  • Knowledge of time-ordered products in quantum mechanics
  • Basic concepts of Feynman propagators
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  • Study Wick's theorem applications in quantum field theory
  • Learn about higher-order contractions in phi^{3} theory
  • Research the derivation of time-ordered products in quantum mechanics
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The discussion is beneficial for theoretical physicists, graduate students in quantum field theory, and researchers focusing on perturbative calculations in quantum mechanics.

Dixanadu
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Hi guys,

So basically I'm trying to find the time ordered product:

T(:\phi^{3}(x)::\phi^{3}(y):)

for a phi^{3} theory and I'm really having trouble counting the Wick contractions. I've counted the first order contractions which I found to be 9. Second order I got 12 but I don't know if its right, and 3rd order is hopeless. So here's where I'm at so far:

T(:\phi^{3}(x)::\phi^{3}(y):)\\<br /> =:\phi^{3}(x)\phi^{3}(y):+9i\Delta_{F}(x-y):\phi^{2}(x)\phi^{2}(y):+12(i\Delta_{F}(x-y))^{2}:\phi(x)\phi(y): + A(i\Delta_{F}(x-y))^{3}

and I don't know if the factor of 12 is right, or how to find A. I need help!

Thanks guys!
 
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Okay I think i got A = 6 but no idea lol...:\
 

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