The -matrix in quantum electrodynamics may be calculated alternatively from the Hamiltonian density and a Hamiltonian in which the Coulomb interaction of the charges and the interaction of the currents with the transverse field are separated. Both procedures are equivalent. Care must be taken, however, to define correctly the initial states, in particular the vacuum state. The definition of the vacuum state in both representations is discussed and the equivalence of the corresponding -matrices is proven.
- Received 9 January 1950
- Published in the issue dated April 1950
© 1950 The American Physical Society