In mathematical physics, the Belinfante–Rosenfeld tensor is a modification of the energy–momentum tensor that is constructed from the canonical energy–momentum tensor and the spin current so as to be symmetric yet still conserved. In a classical or quantum local field theory, the generator of Lorentz transformations can be written as an integral of a local current Here is the canonical Noether energy–momentum tensor, and is the contribution of the intrinsic (spin) angular momentum. Local conservation of angular momentum requires that An integration by parts shows that