Generalized symmetries and conservation laws of (1 + 1)-dimensional Klein–Gordon equation

Abstract

Using advantages of nonstandard computational techniques based on the light-cone variables, we explicitly find the algebra of generalized symmetries of the (1 + 1)-dimensional Klein–Gordon equation. This allows us to describe this algebra in terms of the universal enveloping algebra of the essential Lie invariance algebra of the Klein–Gordon equation. Then, we single out variational symmetries of the corresponding Lagrangian and compute the space of local conservation laws of this equation, which turns out to be generated, up to the action of generalized symmetries, by a single first-order conservation law. Moreover, for every conservation law, we find a conserved current of minimal order contained in this conservation law.