QCDFeynmanRuleConvention fixes the sign convention in
the QCD Feynman rules for the ghost propagator and the ghost-gluon
vertex.This is done by setting the value of
QCDFeynmanRuleConvention[GhostPropagator] and
QCDFeynmanRuleConvention[GluonGhostVertex].
The default values are 1 for both, which corresponds to
the convention used in most books. Setting them to -1
enforces the convention that can be found e.g. in the book “Applications
of Perturbative QCD” by R. Field.
Overview, GluonGhostVertex, GhostPropagator.
Enforce the convention as in “Applications of Perturbative QCD” by R. Field.
QCDFeynmanRuleConvention[GhostPropagator] = -1;
QCDFeynmanRuleConvention[GluonGhostVertex] = -1;GHP[p, a, b] // Explicit-\frac{i \delta ^{ab}}{p^2}
GGV[{p, \[Mu], a}, {q, \[Nu], b}, {k, \[Rho], c}] // Explicitg_s k^{\mu } f^{abc}
Back to the standard convention.
QCDFeynmanRuleConvention[GhostPropagator] = 1
QCDFeynmanRuleConvention[GluonGhostVertex] = 11
1
GHP[p, a, b] // Explicit\frac{i \delta ^{ab}}{p^2}
GGV[{p, \[Mu], a}, {q, \[Nu], b}, {k, \[Rho], c}] // Explicitg_s \left(-k^{\mu }\right) f^{abc}