= Global symmetry in field theory
A global symmetry has transformation parameters constant across spacetime and preserves the action. It can relate physically distinct states. Continuous global symmetries give <Noether currents> and conserved charges when boundary fluxes vanish; discrete symmetries do not receive currents from the same infinitesimal theorem. A <gauge redundancy> instead uses local parameters to relate descriptions of the same physical state, except that nontrivial boundary transformations may carry physical charges. The <global phase symmetry of a complex scalar field> is an important internal example.
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