 Operator product expansion

An operator product expansion expresses the short-distance product of local operators as a sum of local operators multiplied by singular coefficient functions.

Operator Product Expansion (OPE) is a powerful mathematical tool used in quantum field theory (QFT) to simplify the computation of correlation functions and physical observables. The OPE allows us to express the product of two local operators at nearby points in spacetime as a sum of other operators, multiplied by singular terms that depend on the distance between those two points. ### Key Concepts: 1. **Local Operators**: In quantum field theory, operators are used to represent physical quantities.