On the Energy-Momentum Tensor of Bopp-Type Non-Local Field
Yôrô Ôno · Progress of Theoretical Physics · 1951
Expanding the characteristic function ε(x) in the Lagrangian in derivatives of δ(x) and applying the variation principle of general relativity, we obtained the symmetrical energy-momentum tensors for the Bopp-type non-local fields. They are free from the defects accompanying the expressions proposed by Bopp and Heisenberg and can be regarded as the most natural extension of the local fields.