The way path integrals are used in quantum field theory is, very roughly speaking, that the probability amplitude of a process going from point v1 to point v2 is an integral over all possible ways of getting from v1 to v2. In our finite-dimensional model, each of these ``ways'' is represented by a point v in Rn and the probability measure assigned to that way is . The integral is what we called before a 2-point function
We continue with the example of the cubic potential
In terms of Wick's Theorem and our graph interpretation of pairings, this becomes:
The k-point correlation functions are similarly defined and calculated. Here is where we begin to see the usual ``Feynman diagrams.''
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