Invariance of a physical theory under spacetime-dependent (local) transformations of an internal symmetry group G. Demanding local G-invariance forces the introduction of a connection (gauge field) Aμ that transforms as Aμ → U Aμ U⁻¹ +…
Invariance of a physical theory under spacetime-dependent (local) transformations of an internal symmetry group G. Demanding local G-invariance forces the introduction of a connection (gauge field) Aμ that transforms as Aμ → U Aμ U⁻¹ +…