Suppose, in whatever dimension and theory, the action $S$ is invariant for a global symmetry with a continuous parameter $\epsilon$. The trick to get the Noether current consists in making the ...
Has anyone ever heard of integrating out fields from classical Lagrangians if they are quadratic?
Continuous symmetry of the action implies a conservation law, but what if equations of motion have a continuous symmetry? Does it imply a conservation law? Also is symmetry of equations of motion ...
In physics total energy is extremal for the static solutions of equation of motions. Can anyone explain this sentence to me?