Error in MSSM_SLHA2__hgg_plugin

Asked by Amin Aboubrahim on 2018-08-14

Hi Olivier,

I am trying to generate the process p p > h3 b with the model MSSM_SLHA2-no_b_mass but it is failing with the message: "No amplitudes generated from process".
So I tried:
import model MSSM_SLHA2__hgg_plugin-no_b_mass -name
which failed to load with this message:

Error detected in "import model MSSM_SLHA2__hgg_plugin-no_b_mass -name"
write debug file MG5_debug
If you need help with this issue please contact us on https://answers.launchpad.net/mg5amcnlo
MadGraph5Error : Unable to evaluate mdl_MW__1 = cmath.sqrt(mdl_MZ__exp__2/2. + cmath.sqrt(mdl_MZ__exp__4/4. - (mdl_aEW*cmath.pi*mdl_MZ__exp__2)/(mdl_Gf*mdl_sqrt__2))): raise error: name 'mdl_aEW' is not defined

Why aren't there any amplitudes for this process? This is a tree level diagram g b -> b h3.
Also, is there a mistake in the why I am loading the second model with hgg_plugin?

Thank you,
Amin

Question information

Language:
English Edit question
Status:
Solved
For:
MadGraph5_aMC@NLO Edit question
Assignee:
No assignee Edit question
Solved by:
Olivier Mattelaer
Solved:
2018-08-15
Last query:
2018-08-15
Last reply:
2018-08-15

Hi,

The MSSM_SLHA2 is not compatible with the hgg plugin.
The way the EW sector is defined is two different in both model and this make the merging to fail.
It is actually quite simple to correct (since this is an ordering error in the parameters.py
But you need then to be very carefull since some quantity that should be identical are defined from two different definition.
This force you to ensure the internal consistency of the EW sector, since MG5aMC will not be able to fix it anymore.

Cheers,

Olivier

PS: Are you sure that you have a coupling h3 b when the b is massless?

Amin Aboubrahim (amin83) said : #2

Hi Olivier,

Thanks for the explanation. I can revert to the 4FS scheme, p p > h3 b b~ but I was hoping the 5FS would work. So I cannot produce diagrams for h3 production through loop induced g g fusion?
The h3 b coupling vanishes for massless b but I was hoping for a non-vanising bottom Yukawa coupling but it seems that this is not implemented.

Thank you again,
Amin

Hi,

> So I cannot produce diagrams for h3 production through loop induced g g fusion?

This model is not NLO ready, so you can not compute loop with it.
You can check the FR website for NLO ready model of MSSM it is likely to exists.

> The h3 b coupling vanishes for massless b but I was hoping for a non-vanising bottom Yukawa coupling but it seems that this is not implemented.

This is not what is the convention for the "no_b_mass" case, but you can define yourself a new restriction file to set the pole mass to zero and not the yukawa mass.
see https://answers.launchpad.net/mg5amcnlo/+faq/2312

Cheers,

Olivier

> On 14 Aug 2018, at 19:47, Amin Aboubrahim <email address hidden> wrote:
>
> Question #672251 on MadGraph5_aMC@NLO changed:
> https://answers.launchpad.net/mg5amcnlo/+question/672251
>
> Status: Answered => Open
>
> Amin Aboubrahim is still having a problem:
> Hi Olivier,
>
> Thanks for the explanation. I can revert to the 4FS scheme, p p > h3 b b~ but I was hoping the 5FS would work. So I cannot produce diagrams for h3 production through loop induced g g fusion?
> The h3 b coupling vanishes for massless b but I was hoping for a non-vanising bottom Yukawa coupling but it seems that this is not implemented.
>
> Thank you again,
> Amin
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

Amin Aboubrahim (amin83) said : #4

Thanks Olivier Mattelaer, that solved my question.