Nobel prize to R. P. Feynman awarded in 1965. Co-winners J. S. Schwinger and S. Tomonaga "for their fundamental work in quantum electrodynamics, with deep-ploughing consequences for the physics of elementary particles''

FEYNMAN 1950

Feynman, R.P.; Mathematical Formulation of the Quantum Theory of Electromagnetic Interaction
Phys. Rev. 80 (1950) 440;

Reprinted in The Physical Review - the First Hundred Years, AIP Press (1995) 990.
Selected Papers on Quantum Electrodynamics, editor J. Schwinger, Dover Publications, Inc., New York (1958) 257.

Abstracts
The validity of the rules given in previous papers for the solution of problems in quantum electrodynamics is established. Starting with Fermi's formulation of the field as a set of harmonic oscillators, the effect of the oscillators is integrated out in the Lagrangian form of quantum mechanics. There results an expression for the effect of all virtual photons valid to all orders in e^{2}/h c. It is shown that evaluation of this expression as a power series in e^{2}/h c gives just
the terms expected by the aforementioned rules. In addition, a relation is established between the amplitude for a given process in an arbitrary unquantized potential and in a quantum electrodynamical field. This relation permits a simple general statement of the laws of quantum electrodynamics. A description, in Lagrangian quantum-mechanical form, of particles satisfying the Klein-Gordon equation is given in an Appendix. It involves the use of an extra parameter analogous to proper
time to describe the trajectory of the particle in four dimensions. A second Appendix discusses, in the special case of photons, the problem of finding what real processes are implied by the formula for virtual processes. Problems of the divergencies of electrodynamics are not discussed.

Related references See also R. P. Feynman, Phys. Rev. 76 (1949) 749;
R. P. Feynman, Phys. Rev. 76 (1949) 769;
R. P. Feynman, Rev. of Mod. Phys. 20 (1948) 367;
S. Tomonaga, Phys. Rev. 74 (1948) 224;
S. Kanesawa and S. Tomonaga, Progr. of Theor. Phys. 3 (1948) 101;
J. Schwinger, Phys. Rev. 76 (1949) 790;
V. Fock, Physik Zeits. Sow. 12 (1937) 404;
F. J. Dyson, Phys. Rev. 75 (1949) 1736;
W. Pauli and F. Villars, Rev. of Mod. Phys. 21 (1949) 434;
E. Fermi, Rev. of Mod. Phys. 4 (1932) 87;
W. Heitler, The Quantum Theory of Radiation, Oxford Univ. Press, London (1944);
Y. Nambu, Progr. of Theor. Phys. 5 (1950) 82;
F. J. Dyson, Phys. Rev. 75 (1949) 486;

Record comments
Mathematical proof of the validity of the Feynman rules for calculations of amplitudes in QED.