Remove spinors on an amplitude generated by FCFAConvert

[JulRovn]

Hello,
I am working with a four-fermion operator and when using the command FCFAConvert and selecting Truncated->True, there is a problem with the DiracJoinChain
That is why I am working setting Truncated->True and then I would like to remove the spinors.
What is the command I should write for FeynArts and/or FeynCalc?
Since I am working at an operator level, I also have want to remove some gamma matrices and SU(3). Is it the same command?
Thank you in advance

[vsht]

Hi,

removing the spinors can be tricky because that leaves you with open Dirac chains
and this is something that FeynCalc is not particularly good at. I guess something like this should work

sps = Cases2[amp, Spinor]
dis = FCMakeSymbols[di, Range[1, Length[sps]], List]
ru = Thread[Rule[sps, dis]]
amp // FCDiracIsolate[#, Head -> dch] & //  ReplaceAll[#,  dch[DOT[a_Spinor, b___, c_Spinor]] :> DCHN[b, a /. ru, c /. ru]] &

Since I am working at an operator level, I also have want to remove some gamma matrices and SU(3). Is it the same command?

If you are new to FeynCalc, there are tutorials and a manual that one should go through first. A good familiarity with Mathematica
programming is also essential here. Sorry, but FeynCalc is not as simple to use as Madgraph & co. and it requires some effort to master the package.

[Gorgeous-Summer]

Hi,
I want to know if I could remove the external vector lines in some Feynman diagrams such as tree diagram of photon gluon fusion? thamks.

[vsht]

You'd need some custom code for that.

[Gorgeous-Summer]

I import the StandardForm and substitute what I want