MadGraph5_aMC@NLO

generating events for pp>thq process

Asked by Shubhani Jain

Hi

I am trying to generate process pp>thq using 2HDMtII_NLO model, but it gives me error everytime I try to generate the process:

define q = u c d s u~ c~ d~ s~
generate p p > t h1 q [QCD]

Command "generate p p > t h1 q " interrupted in sub-command:
"generate p p > t h1 q" with error:
NoDiagramException : No amplitudes generated from process Process: g/u/c/d/s/u~/c~/d~/s~ g/u/c/d/s/u~/c~/d~/s~ > t h1 u/c/d/s/u~/c~/d~/s~ WEIGHTED=12 @1. Please enter a valid process

I have even tried defining top =t t~ and use j instead of q but gives me the same error. Any help would be much appreciated.

Thanks
Regards

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Olivier Mattelaer (olivier-mattelaer) said : 		#1

hi,

I do not know the model, but since you have a top in the final state, I guess that the issue is that you need a five flavor model and not a four flavour model like the one you use.

You can use either re-generate the Feynrules model to be in 5 flavor (which is the most optimal method)
or you can use a model restriction (see https://answers.launchpad.net/mg5amcnlo/+faq/2312 <https://answers.launchpad.net/mg5amcnlo/+faq/2312>) to set the b mass to zero.

If that is not your issue, then I would need to see which type of Feynman diagram you are expecting for such model.

Cheers,

Olivier

> On 28 Sep 2021, at 10:35, Shubhani Jain <email address hidden> wrote:
>
> 2HDMtII_NLO

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Shubhani Jain (s2697661) said : 		#2

Hi Olivier

Thanks for the reply.

Yes, you are right adding b b~ to q definition solved the issue for me.

Regards
Shubhani

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Shubhani Jain (s2697661) said : 		#3

Hi Olivier

Sorry for opening this query again.

I am trying to generate process p p > t h q using 2HDMtII_nlo model, with q definition now have bb~ as well. I want to decay :

t >b w+ , w+ > l+ vl
t~ > b~ w- , w- > l- vl~
h > z z , z >l+ l-

But when I define these decay in madspin it gives me an error. Is there something wrong with the way I define things?

Any help would be much appreciated.

Thanks
Shubhani

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Olivier Mattelaer (olivier-mattelaer) said : 		#4

h > z z , z >l+ l-

This decay is impossible since an onshell Higgs can not decay to two onshell Z.
Addtionally decaying the Higgs within MadSpin is irrelevant since they are not production-decay spin correlation (the higss is spin 0)
and the off-shell effect are also negligeable (the Higss width is too small to be relevant experimentally).

Cheers,

Olivier

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Shubhani Jain (s2697661) said : 		#5

Thanks Olivier, that solved my confusion

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