Abstract
If one wishes to derive generalized field equations from a Lagrangian, at the same time preserving the linear character of the equations, one must admit terms involving derivatives of the field quantities. It turns out that the only non-trivial generalization of this kind, leading to differential equations of order below eighth, is obtained by taking . This leads to a theory that contains the Landé-Thomas theory and accounts for the choice of sign required when one wishes to consider the total field as consisting of the Maxwell-Lorentz and the Yukawa fields.
- Received 23 March 1942
DOI:https://doi.org/10.1103/PhysRev.62.68
©1942 American Physical Society