How gauge covariance of the fermion and boson propagators in QED constrain the effective fermion-boson vertex

Shaoyang Jia, M. R. Pennington
2016 Physical Review D  
We derive the gauge covariance requirement imposed on the QED fermion-photon three-point function within the framework of a spectral representation for fermion propagators. When satisfied, such requirement ensures solutions to the fermion propagator Schwinger-Dyson equation (SDE) in any covariant gauge with arbitrary numbers of spacetime dimensions to be consistent with the Landau-Khalatnikov-Fradkin transformation (LKFT). The general result has been verified by the special cases of three and
more » ... ases of three and four dimensions. Additionally, we present the condition that ensures the vacuum polarization is independent of the gauge parameter. As an illustration, we show how the Gauge Technique dimensionally regularized in 4D does not satisfy the covariance requirement.
doi:10.1103/physrevd.94.116004 fatcat:6gn3fzhwzrhznjhfbvzypocr2y