Boldo, J. L. [UNESP]Pimentel, B. M. [UNESP]Tomazelli, J. L. [UNESP]2014-05-272014-05-271997-07-01International Journal of Theoretical Physics, v. 36, n. 7, p. 1565-1574, 1997.0020-7748http://hdl.handle.net/11449/65130The operator S in Fock space which describes the scattering and particle production processes in an external time-dependent electromagnetic potential A can be constructed from the one-particle S-matrix up to a physical phase λ[A]. In this work we determine this phase for QED in (2 + 1) dimensions by means of causality and show that no ultraviolet divergences arise, in contrast to the usual formalism of QED3.1565-1574engArtigo10.1007/BF02435756WOS:A1997XT79900005Acesso restrito2-s2.0-0031475541