How to Count Wick Contractions in Phi^3 Theory?

  • Context: Graduate 
  • Thread starter Thread starter Dixanadu
  • Start date Start date
  • Tags Tags
    Counting
Join the discussion
Ask a follow-up here, or get your own question answered by working scientists, mathematicians and engineers — people, not an autocomplete.
Real named experts · corrections over time · the nuance an AI answer skips
1 reply · 2K views
Dixanadu
Messages
250
Reaction score
2
Hi guys,

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

[itex]T(:\phi^{3}(x)::\phi^{3}(y):)[/itex]

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:

[itex]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}[/itex]

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

Thanks guys!
 
Physics news on Phys.org
Okay I think i got A = 6 but no idea lol...:\