 Background field method

The Background Field Method (BFM) is a technique used in theoretical physics, particularly in quantum field theory, to simplify the calculations involving quantum fields. This method involves separating the fields into a "background" part and a "fluctuation" part. ### Key Concepts: 1. **Background Field**: In this context, the background field represents a classical configuration or solution of the field equations. It is treated as a fixed, external influence on the quantum fields.