Identifying Contributions of different Parameter orders in MG v3.1.X

Asked by Philip Keicher

Dear experts,

I'm generating events with MG5 v3.1.0 at NLO. The model I use is designed to simulate processes under consideration of EFT effects and introduces a parameter for the orders of new physics (NP) beyond the SM. The model also introduces new parameters which control the contribution of new operators.

I would like to generate the different contributions to the overall cross section, i.e. the pure EFT part and the interference terms, separately. However, I'm still a novice in MG, so I'm not sure how to do this correctly. As far as I know, syntax like NP^2==X does not work in the NLO mode. So I came up with the following options

1) Calculate the processes with NP^2=X, which will generate more contributions than I want. I should then be able to extract the individual components by subtracting cross sections. For example, if I generate NP^2=0 (i.e. the SM) and NP^2=2 (i.e. the pure EFT part + SM) and subtract the two, I should get the pure EFT part.

2) Use the information given of the orders_tag_plot feature in MG v3.1.X. Here, I would have to select and add the components with NP==2 to get the pure EFT part.

Here are my questions: Can I really do it like this? Are the two options equivalent (if they are valid at all)? Are there any pitfalls that I should be aware of?

Thanks in advance for your help!

Cheers,
Philip

Question information

Language:
English Edit question
Status:
Solved
For:
MadGraph5_aMC@NLO Edit question
Assignee:
Eleni Vryonidou Edit question
Solved by:
Eleni Vryonidou
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Philip Keicher (pkeicher) said :
#1

Dear all,

is there any news regarding this question? Is there any information missing?

Cheers,
Philip

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Olivier Mattelaer (olivier-mattelaer) said :
#2

This is only 3 days old topic and since we are in holliday it is possible that Eleni is currently in holliday and will reply you when she will be back.

Cheers,

Olivier

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Philip Keicher (pkeicher) said :
#3

Of course, sorry - I didn't mean to pressure too much, just thought I'd ping you again.

Enjoy the holidays!

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Best Eleni Vryonidou (evryonidou) said :
#4

Hi Philip,

see comments below:

1) Calculate the processes with NP^2=X, which will generate more contributions than I want. I should then be able to extract the individual components by subtracting cross sections. For example, if I generate NP^2=0 (i.e. the SM) and NP^2=2 (i.e. the pure EFT part + SM) and subtract the two, I should get the pure EFT part.

NP^2=2 will give you the SM and the interference of the EFT with the SM. You can subtract NP=0 to get the interference. Similarly you can do NP^2=4 to get the sum of SM+interference+EFT squared terms. This should work fine. You can also optimise the coefficient values to have better precision.

2) Use the information given of the orders_tag_plot feature in MG v3.1.X. Here, I would have to select and add the components with NP==2 to get the pure EFT part.

This should also be possible but you would need to build an analysis reading the various weights. I have not tried it myself with event generation so I am not sure how to do it exactly. Maybe Marco Zaro can help you more with that.

But I think option 1 should work fine.

Cheers,

Eleni

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Philip Keicher (pkeicher) said :
#5

Thanks Eleni Vryonidou, that solved my question.