Insufficient pseudorapidity-eta cut

Asked by Max Fieg on 2021-02-18

Hello

I am looking at the process p p > b b~ and looking at the resulting neutrinos that come out. I am interested in neutrinos that only go in a certain pseudorapidity range (<5 , <2 , etc.). But when I apply the cuts, and then calculate the pseudorapidity of the resulting neutrinos as a check, I find that the cut does not seem to be done to full effect.

I have tried
-Setting a cut on etab. This seems to have a strong effect, but when I do etab < 2 for example, I only get ~30% of neutrinos with eta < 2
-I have tried setting this etab cut in addition to eta_max_pdg for the neutrinos specifically. This eta_max_pdg cut did not seem to change things very much, with or without the etab cut.
-I have also tried setting this eta_max_pdg for B mesons, and roughly the same issue occurs.

Am I misunderstanding something? Naively, I would think that all I would need is to set a cut on the neutrino via eta_max_pdg ; but as I said this does not seem to enforce a very strong cut.

Any advice or resources is appreciated.
Thank you

Question information

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MadGraph5_aMC@NLO Edit question
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Last query:
2021-02-18
Last reply:
2021-02-18

Those cuts are before the parton shower.
So at that stage you only have 2 b quark on which to cut.

If you want cuts on the neutrino/B meson, this will not be in the run_card that such cuts need to be specified but in the pythia8_card.dat. (If this is possible to do).
I would advise you to check the pythia8 manual if such cuts are possible or not

Cheers,

Olivier

> On 19 Feb 2021, at 00:05, Max Fieg <email address hidden> wrote:
>
> New question #695634 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/695634
>
> Hello
>
> I am looking at the process p p > b b~ and looking at the resulting neutrinos that come out. I am interested in neutrinos that only go in a certain pseudorapidity range (<5 , <2 , etc.). But when I apply the cuts, and then calculate the pseudorapidity of the resulting neutrinos as a check, I find that the cut does not seem to be done to full effect.
>
> I have tried
> -Setting a cut on etab. This seems to have a strong effect, but when I do etab < 2 for example, I only get ~30% of neutrinos with eta < 2
> -I have tried setting this etab cut in addition to eta_max_pdg for the neutrinos specifically. This eta_max_pdg cut did not seem to change things very much, with or without the etab cut.
> -I have also tried setting this eta_max_pdg for B mesons, and roughly the same issue occurs.
>
> Am I misunderstanding something? Naively, I would think that all I would need is to set a cut on the neutrino via eta_max_pdg ; but as I said this does not seem to enforce a very strong cut.
>
> Any advice or resources is appreciated.
> Thank you
>
> --
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> contact for MadGraph5_aMC@NLO.

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