A class of transformations on the Dirac Hamiltonian

Abstract

We give a new generalization of the Foldy-Wouthuysen transformation and show a simple and elegant method of obtaining explicit forms of the Foldy-Wouthuysen transformation and its generalizations by using the U-matrix method of Ramakrishnan. We also show how this method can be used to obtain the transformation which connects the Dirac equation to the non-covariant form of the Dirac equation recently discussed in the literature.