Algebraic computation of radiative corrections for electron-proton scattering

Abstract Algebraic computer programmes written largely in the language LISP have been developed to derive matrix elements from arbitrary Feynman diagrams, conduct mixed integral-substitution and trace operations on long expressions containing Dirac γ matrices, and help to write programmes in FORTRAN for numerical evaluation of these expressions after simplification. The programmes in LISP have been applied to the calculation of radiative corrections to electron-proton scattering with an accuracy that has not been available in previous results. The calculation includes a contribution from the excitation of the N*(33) resonance in two-photon exchange Feynman diagrams that has involved the sorting of at least 162 000 algebraic terms by an IBM 7090 computer.