 Conserved current

A conserved current is a vector field $j^{\mu }$ satisfying the continuity equation ${\partial }_{\mu }{j}^{\mu }=0$. Its spatial integral is constant in time when no current crosses the boundary.

In physics, particularly in the context of field theory and particle physics, a "conserved current" refers to a current that is associated with a conserved quantity in a dynamical system. This concept is heavily rooted in the principles of symmetry, notably through Noether's theorem, which connects symmetries of the action of a physical system to conserved quantities.