gauge invariance [`gāj in`ver·ē·ǝns] ELECTROMAGNETISM The invariance of electric and magnetic fields and electrodynamic interactions under gauge transformations. PHYSICS The invariance of any field theory under gauge transformations. QUANTUM MECHANICS An invariance of a Lagrangian based on an internal gauge group, such as U(1) for electromagnetism or U(1) × SU(2) for the Weinberg-Salam unified model of weak and electromagnetic interactions. |