MadGraph5_aMC@NLO

BW Cuttoff and min invariant mass of jets

Asked by Gabriel Vian

Dear MadGraph Experts,

I'm trying to generate ttHH and tt4b processes

1) I would like to know if it setting

#**********************************
  15000.0 = bwcutoff ! (M+/-bwcutoff*Gamma)
#**********************************************************

for ttHH would be problematic.

2) And also if setting

  10.0 = mmjj ! min invariant mass of a jet pair
  10.0 = mmbb ! min invariant mass of a b pair

for tt4b would be problematic.

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Olivier Mattelaer
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Olivier Mattelaer (olivier-mattelaer) said : 		#1

So yes, setting bwcutoff that large can only be problematic.
Since this will break the NWA approximation that you are using.

For the cut, it can be ok (but please test).

Olivier

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Gabriel Vian (gabriel-vian-24) said : 		#2

Dear Olivier,

Thank you very much for this quick answer.
If I was only calculating ttHH, without any decay, the btwcutoff value would still be relevant?

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Best Olivier Mattelaer (olivier-mattelaer) said : 		#3

It will impact the format of the lhef file and how the parton shower will be run so yes it still has relevance.

Such parameter should not be that large.

Olivier

> On 6 Nov 2024, at 21:40, Gabriel Vian <email address hidden> wrote:
>
> Question #819284 on MadGraph5_aMC@NLO changed:
> https://answers.launchpad.net/mg5amcnlo/+question/819284
>
> Status: Answered => Open
>
> Gabriel Vian is still having a problem:
> Dear Olivier,
>
> Thank you very much for this quick answer.
> If I was only calculating ttHH, without any decay, the btwcutoff value would still be relevant?
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

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Gabriel Vian (gabriel-vian-24) said : 		#4

Thanks Olivier Mattelaer, that solved my question.

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Sihyun Jeon (shjeon) said : 		#5

The cut is from me within CMS discussion.

It is "fine" to have the cut in a sense that it's OK to use that cut as long as you know the consequences having the cut.
e.g. It is "fine" to have the cut on dilepton mass 500GeV and make LHE files. But it is NOT fine to have the cut like that if you say your aim is to Z mass measurement cuz you are cutting off all onshell Z boson contributions.

The question is, what is your analysis aim and what are you trying to do with that sample. If you are requiring dijet mass to be always above 10 gev for every single pair for whatever reason, it's fine, but is this the case is the question. You can follow up in cms genproductions.