EtaSign
is an option for SFAD
, GFAD
, CFAD
and other objects representing propagators. It specifies the default sign of the prescription in the propagators, e.g. for standard Feynman propagators the value 1
corresponds to , while the value -1
sets .
Notice that if the sign of is already specified in the propagator, e.g.
[{q, {m^2, 1}}] CFAD
then this specification always overrides the EtaSign option. Hence
[{q, {m^2, 1}}, EtaSign -> -1] CFAD
still has the positive .