Manuscript V@1 · V.tex · figure · e7ddf37d
External first retarded coefficient
The external-metric first retarded product › Representation and the external coefficient · lines 2308–2339
V@1#fig:external-contraction
metricscalarrepresented quantumdefect / unresolvedsupport / scope
Time-ordered product
normal three-scalar block
one cross-contraction
Ordinary product
the same normal block
one cross-contraction
retarded subtraction
— normal blocks cancel
At most one cross-contraction. No double-contraction vacuum block. Off-shell labels stay until the product is constructed. Not a loop diagram.
External first retarded coefficient. The two products have the same completely normal-ordered three-scalar block, which cancels in the retarded subtraction. Their single cross-contractions differ by , leaving a linearly smeared free field with compact test . The off-shell insertion label is retained until the product is constructed.