# Relating on-shell and off-shell formalism in perturbative quantum field theory

October 16, 2007

In the on-shell formalism (mostly used in perturbative quantum field theory) the entries of the time ordered product T are on-shell fields (i.e. the basic fields satisfy the free field equations). With that, (multi)linearity of T is incompatible with the Action Ward identity. This can be circumvented by using the off-shell formalism in which the entries of T are off-shell fields. To relate on- and off-shell formalism correctly, a map sigma from on-shell fields to off-shell fields was introduced axiomatically by Duetsch and Fredenhagen. In that paper it was shown that, in the case of one real scalar field in $N=4$ dimensional Minkowski space, these axioms have a unique solution. However, this solution was given there only recursively. We solve this recurrence relation and give a fully explicit expression for sigma in the cases of the scalar, Dirac and gauge fields for arbitrary values of the dimension $N$.

open access link
J.Math.Phys.49:052303,2008

@article{Brouder:2007db,
author = "Brouder, Christian and Dutsch, Michael",
title = "{Relating on-shell and off-shell formalism in
perturbative quantum field theory}",
journal = "J. Math. Phys.",
volume = "49",
year = "2008",
pages = "052303",
doi = "10.1063/1.2918137",
eprint = "0710.3040",
archivePrefix = "arXiv",
primaryClass = "hep-th",
SLACcitation = "%%CITATION = ARXIV:0710.3040;%%"
}

Keywords:

off shell formalism, perturbative AQFT