Conserved quantities from piecewise Killing vectors

Abstract

In the presence of symmetries, conserved quantities can be obtained by contracting the stress-energy tensor with a killing vector. We generalize this result to piecewise Killing vectors by giving sufficient conditions for the construction of an associated conserved quantity. A typical example namely, namely two stationary space-times joined together in such a way that the resulting space-time is not stationary, is treated in detail.