ABSTRACT
Quantum electrodynamics is an example of a U(1) gauge theory. U(1) is the group of the unimodular complex numbers and determines the transformation of the charged fields () https://www.w3.org/1998/Math/MathML"> Ψ ( x ) → exp ( − i q Λ ( x ) ) Ψ ( x ) ≡ g ( x ) Ψ ( x ) . https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429073601/03ca065d-1bf0-4218-811d-2f95276252a3/content/equ_1109.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/>
