Partition function (quantum field theory)
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In quantum field theory, we have a generating functional, Z[J] of correlation functions and this value, called the partition function is usually expressed by something like the following functional integral:
- <math>\int \mathcal{D}\phi e^{i(S[\phi]+\int d^dx J(x)\phi(x))}<math>
where S is the action functional. This is very analogous to statistical mechanics. In fact, a Wick rotation emphasizes the similarities.