Name: Jon Palmer Date: 04/29/04-10:02:59 PM Z


I am having some issues using the CreateFCAmp function specifically
specifying the level at which the fields are calculated.

For various reasons I want to only insert fields at the “{Particles}” level.
However when I then run CreateFCAmp on those inserted fields I get an error
from CreateFeynAmp. With $VeryVerbose on high it prints

“creating amplitudes at level(s) {Generic, Classes}”

and then reports two errors

“CreateFeynAmp::nolevel: Warning: Level Generic is not contained in this
insertion.”
“CreateFeynAmp::nolevel: Warning: Level Classes is not contained in this
insertion.”

as the inserted fields at both the Generic and Classes levels are obviously
empty. I believe that CreateFeynAmp is supposed to default to the level at
which the fields are inserted but that doesn’t appear to happen when it is
called through CreateFCAmp (No such error results if I call CreaateFeynAmp
directly on the inserted fields). I have also tried to force the issue by
specifying “AmplitudeLevel -> {Particles}” as an option for CreateFCAmp but
it makes no difference. Any thoughts as to why it behaves like this and how
it might be rectified?

Many thanks,
Jon Palmer