MadGraph5_aMC@NLO

Setting Phase space point with ML5 within Madgraph

Asked by Florian Lyonnet

Hi all,

I am trying to run some cross checks using the [virt=QCD] option from within Madgraph 5v2. Once the desired process has been generated I want to get the result for the virtual by running the launch command. Then, when asked I try to change the phase space point either directly by editing the PS.input file in the command line or by feeding in a new file in which the point is defined. However, I always get the same result for the phase space point :

5.0000000000000000E+02 0.0000000000000000E+00 0.0000000000000000E+00 5.0000000000000000E+02
5.0000000000000000E+02 0.0000000000000000E+00 0.0000000000000000E+00 -5.0000000000000000E+02
5.0000000000000000E+02 4.2317680317927102E+02 5.6744129776637998E+01 -1.9435147796418900E+02
5.0000000000000000E+02 -4.2317680317927102E+02 -5.6744129776637998E+01 1.9435147796418900E+02

I checked that the points I am providing satisfy momentum conservation.

In addition, I'd like to know if when askin to generate the process u u~ > ... the result I obtain is actually including the contribution u~ u > ... as well or not ?

Thanks in advance for your time,

Best,

Florian Lyonnet

Question information

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Status:
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MadGraph5_aMC@NLO Edit question
Assignee:
Valentin Hirschi Edit question
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Revision history for this message
Valentin Hirschi (valentin-hirschi) said : 		#1

Hi Florian,

Sorry for the late answer.
I tried that with the latest version 2.0.0 and it seems to correctly read in the PS point specified.
Could you confirm that you are still having this issue with the latest version?

Concerning your second question, the answer is that when running MadLoop in stand-alone, you get the evaluation of the loop matrix element squared for the channel you explicitly asked for exactly, so that the channel with swapped initial states is not factored in. Notice however that the loop matrix element (as well as the Born one) do include the identical final state symmetry factors.

Revision history for this message
Florian Lyonnet (dibus2) said : 		#2

Hi Valentin,

I actually do not face this issue anymore.Thank you very much for your
answer.

Best,

Florian
Your question #240257 on MadGraph5_aMC@NLO changed:
https://answers.launchpad.net/madgraph5/+question/240257

    Status: Open => Needs information

Valentin Hirschi requested more information:
Hi Florian,

Sorry for the late answer.
I tried that with the latest version 2.0.0 and it seems to correctly read
in the PS point specified.
Could you confirm that you are still having this issue with the latest
version?

Concerning your second question, the answer is that when running MadLoop
in stand-alone, you get the evaluation of the loop matrix element
squared for the channel you explicitly asked for exactly, so that the
channel with swapped initial states is not factored in. Notice however
that the loop matrix element (as well as the Born one) do include the
identical final state symmetry factors.

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Revision history for this message
Valentin Hirschi (valentin-hirschi) said : 		#3

Issue closed.

Revision history for this message
Steven Jeremies (minits) said : 		#4

Hi Florian,

I stumbled upon your post because I have the same question. Since the question has been solved here I just wanted to ask where to finde the PS.input file. Thanks in advance!

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