Reduction formulas for charged particles and coherent states in quantum electrodynamics

Daniel Zwanziger

    Research output: Contribution to journalArticlepeer-review


    A weak asymptotic limit is proposed for a charged field as an operator on the space of asymptotic states. This leads to a modified Lehmann-Symanzik-Zimmermann reduction formula and a determination of the singularity near the mass shell of the Green's function of a charged particle in the presence of other charged particles. Coherent states of the electromagnetic field are also reduced out. The resultant expression for S-matrix elements in terms of vacuum expectation values of time-ordered fields yields a slight elaboration of the Feynman rules which allows a perturbative calculation that is free of infrared and Coulombic divergences order by order. As an application, the amplitude for scattering of a Dirac particle by an external Coulomb potential is calculated to second order in the external potential, with a finite result.

    Original languageEnglish (US)
    Pages (from-to)1082-1099
    Number of pages18
    JournalPhysical Review D
    Issue number4
    StatePublished - 1973

    ASJC Scopus subject areas

    • Physics and Astronomy (miscellaneous)


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