how to get contribution from a particular Feynman diagram?

Hi,

Not it is not possible.

Now you can still modify the generated code to do whatever you want with it.
if you modify all the SubProcesses/P*/matrix*.f, you can obtain that effect.

In those file, you have line like this:

      CALL IXXXXX(P(0,1),ZERO,NHEL(1),+1*IC(1),W(1,1))
      CALL OXXXXX(P(0,2),ZERO,NHEL(2),-1*IC(2),W(1,2))
      CALL IXXXXX(P(0,3),ZERO,NHEL(3),-1*IC(3),W(1,3))
      CALL OXXXXX(P(0,4),ZERO,NHEL(4),+1*IC(4),W(1,4))
      CALL FFV1P0_3(W(1,1),W(1,2),GC_2,ZERO,ZERO,W(1,5))
C Amplitude(s) for diagram number 1
      CALL FFV1_0(W(1,3),W(1,4),W(1,5),GC_3,AMP(1))
      CALL FFV2_5_3(W(1,1),W(1,2),GC_51,GC_58,MDL_MZ,MDL_WZ,W(1,5))
C Amplitude(s) for diagram number 2
      CALL FFV2_4_0(W(1,3),W(1,4),W(1,5),GC_50,GC_59,AMP(2))

If you want only the diagram 2 in that case, you can replace this set of line by

      CALL IXXXXX(P(0,1),ZERO,NHEL(1),+1*IC(1),W(1,1))
      CALL OXXXXX(P(0,2),ZERO,NHEL(2),-1*IC(2),W(1,2))
      CALL IXXXXX(P(0,3),ZERO,NHEL(3),-1*IC(3),W(1,3))
      CALL OXXXXX(P(0,4),ZERO,NHEL(4),+1*IC(4),W(1,4))
      CALL FFV1P0_3(W(1,1),W(1,2),GC_2,ZERO,ZERO,W(1,5))
C Amplitude(s) for diagram number 1
      AMP(1) = 0
      CALL FFV2_5_3(W(1,1),W(1,2),GC_51,GC_58,MDL_MZ,MDL_WZ,W(1,5))
C Amplitude(s) for diagram number 2
      CALL FFV2_4_0(W(1,3),W(1,4),W(1,5),GC_50,GC_59,AMP(2))

Cheers,

Olivier

On 10 Jun 2015, at 07:16, satendra kumar <email address hidden> wrote:

> New question #267968 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/267968
>
> Hi Olivier,
>
> Is it possible to get contribution from a particular Feynman diagram in Madgraph?. If it is so, then please explain how to proceed?
>
>
> Thanks
>
> --
> You received this question notification because you are an answer
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