Abstract:
Local symmetries and conserved densities are calculated for a system of classical
scalar fields in $(n+1)$-dimensional ($n>1$) space-time with Lagrangian of the form
$$
L=\frac12h_{ab}(\varphi){\varphi_\nu}^a\varphi^{b\nu}-V(\varphi).
$$
It is shown that, in contrast to two-dimensional theories, the existence of higher
symmetries or conservation laws is possible only if in the field equations one can
separate a linear subsystem by means of a point transformation $\varphi^a=f^a(\bar\varphi)$. In the case of an irreducible metric $h_{ab}$, all symmetries and conserved densities are found
explicitly. An equation is obtained for the local conserved densities of an arbitrary
generalized-evolution system.