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Generation of TTZZ sample without MadSpin card #3815

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G-Vian
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@G-Vian G-Vian commented Dec 5, 2024

Dear GEN team,

My team wants a ttZZ sample with 13.6 TeV center of mass energy. The other TTZZ card, available at [1], contains a MadSpin Card that decays the ZZ, that's why I created these cards for a TTZZ process without Z decaying.
Thank you very much.

@bbilin
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bbilin commented Dec 12, 2024

Thanks. I think the tops need to be decayed in the Madgraph. (or madspin)

@G-Vian
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G-Vian commented Dec 12, 2024

Dear Bugra,

I didn't request the top's decay, as my team wants this sample with the top decaying inclusive.
Thank you very much!

@lviliani
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Dear @G-Vian, in this case the decays will be handled by pythia8, which does not take into account spin correlations effects in the decays. This will lead to wrong distributions for spin sensitive observables.
If you want inclusive decays, the best way is still to use Madgraph or Madspin to handle them.

@G-Vian
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G-Vian commented Dec 13, 2024

Dear Lorenzo,
Thanks for your prompt answer.
I modified the proc card, adding the decay of the tops.

@lviliani
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lviliani commented Jan 8, 2025

Dear @G-Vian , thanks for following up and sorry for the late response.
I think it would be even better to include the full decay chain, i.e. also the W decays.

But actually, referring also to the other TTZZ card that you mentioned at the beginning, what is the difference here? It looks to me that in both cases you will get inclusive decays.

@G-Vian
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G-Vian commented Jan 8, 2025

Dear Lorenzo,
We would like to keep the W undecayed because we want to explore different channels from these decays.
Additionally, the previous TTZZ card had a MadSpin Card that decays the ZZ, which was undesirable.

@lviliani
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lviliani commented Jan 8, 2025

Sorry, I'm not following.
In the previous TTZZ card you are decaying top and Z to all, which means they are inclusive in the decays and your samples will contain all the decay channels.
Now, if you don't decay Z and top in madgraph/madspin, it will be decayed later on by Pythia8 to all possible channels, so you will get an inclusive sample anyway.

@G-Vian
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G-Vian commented Jan 8, 2025

Yes, thats correct.

@lviliani
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lviliani commented Jan 8, 2025

Ok thanks, then I don't understand why you need these new TTZZ cards.

@G-Vian
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G-Vian commented Jan 8, 2025

It is because we dont want the MadSpin decay of the Zs

@sihyunjeon
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sihyunjeon commented Jan 8, 2025

But then why decay top in madgraph?

Setup is not superbly convincing

Either you drop all the decays in madgraph/madspin to enhance computing performance (pythia is faster) OR decay both t and z

You decay top down to w and b. Why? Pythia decays top to w and b anyways

You can do
decay z > all all
If you want inclusive z decays

Or are we missing sth here

@G-Vian
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G-Vian commented Jan 8, 2025

I have decayed the Tops because was informed in the previous comment that leaving it to Pythia decay would lead to wrong spin correlations.

@sihyunjeon
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Same story goes for z, it loses spin correlation when pythia handles it

@lviliani
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lviliani commented Jan 8, 2025

To me the proper configuration is the previous one, in which you use madspin for all the decays.

Maybe if you explain why you don't want madspin we can have a better understanding.

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4 participants