model can not handle loop process

Asked by Basabendu on 2019-12-04

Dear Authors,

I am trying to generate a BSM process similar to h > a a in Madgraph using Feynrules UFO files. I am generating the files at NLO but my model file is incapable of generating h > a a itself, and showing an error: 'can not handle loop process.' I am writing this process as:

generate h > a a [noborn=qed]

I am unable to find my mistake. Kindly help me out.

Thank you.

Question information

Language:
English Edit question
Status:
Solved
For:
MadGraph5_aMC@NLO Edit question
Assignee:
No assignee Edit question
Solved by:
Olivier Mattelaer
Solved:
2019-12-04
Last query:
2019-12-04
Last reply:
2019-12-04

Did you use NLOCT?
This the extension of FR that is needed for the computation of the R2 counter-term needed for the computation of the loop to make the model able to handle loop process

Cheers,

Olivier

> On 4 Dec 2019, at 15:32, Basabendu <email address hidden> wrote:
>
> New question #686658 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/686658
>
> Dear Authors,
>
> I am trying to generate a BSM process similar to h > a a in Madgraph using Feynrules UFO files. I am generating the files at NLO but my model file is incapable of generating h > a a itself, and showing an error: 'can not handle loop process.' I am writing this process as:
>
> generate h > a a [noborn=qed]
>
>
> I am unable to find my mistake. Kindly help me out.
>
>
> Thank you.
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

Basabendu (bb1988-1) said : #2

Hi Olivier,

Yes I have used NLOCT. I am exactly following the steps in the SM.nb file provided in the SM folder. But still it is not providing me h > a a process.

h > a a is not a QCD loop so actually NLOCT might not be able to handle such computation.
For the SM, we actually have created the model by hand and not via FeynRules.

I would suggest to contact NLOCT authors to check if they can compute what you need (and how to do it)

Cheers,

Olivier

> On 4 Dec 2019, at 16:08, Basabendu <email address hidden> wrote:
>
> Question #686658 on MadGraph5_aMC@NLO changed:
> https://answers.launchpad.net/mg5amcnlo/+question/686658
>
> Status: Answered => Open
>
> Basabendu is still having a problem:
> Hi Olivier,
>
> Yes I have used NLOCT. I am exactly following the steps in the SM.nb
> file provided in the SM folder. But still it is not providing me h > a a
> process.
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

Basabendu (bb1988-1) said : #4

Thanks Olivier Mattelaer, that solved my question.