MadGraph5_aMC@NLO

quartic scalar coupling in mssm

Asked by Francesco Dighera

Dear MadTeam,

I am using MadGraph_v1_5_2 to compute some tree level stau-stau annihilation at low relative velocity in the MSSM.
I have an issue with the process ta1+ ta1- > h1 h1 that seems to be related with the quartic coupling involving the 2 staus and the 2 Higgs bosons.
I tried to look for this vertex in the "vertices.py" file but I couldn't find it.
Is there a way to include this vertex?

Thanks in advance and best regards,
Francesco

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Olivier Mattelaer (olivier-mattelaer) said : 		#1

Hi Francesco,

All the 4 scalar interactions are by default removed from any output created by FR. In addition to their limited physical impact, the number of such interactions are so huge that
this makes the code to slow down by a very huge factor.

The solution is to use FeynRules and to use the following syntax for generating the model:
WriteUFO[L, Exclude4Scalars->False]
(Thanks to Celine Degrande for the syntax)

Cheers,

Olivier

On Jun 11, 2013, at 9:35 AM, Francesco Dighera <email address hidden> wrote:

> New question #230580 on MadGraph5:
> https://answers.launchpad.net/madgraph5/+question/230580
>
> Dear MadTeam,
>
> I am using MadGraph_v1_5_2 to compute some tree level stau-stau annihilation at low relative velocity in the MSSM.
> I have an issue with the process ta1+ ta1- > h1 h1 that seems to be related with the quartic coupling involving the 2 staus and the 2 Higgs bosons.
> I tried to look for this vertex in the "vertices.py" file but I couldn't find it.
> Is there a way to include this vertex?
>
> Thanks in advance and best regards,
> Francesco
>
> --
> You received this question notification because you are a member of
> MadTeam, which is an answer contact for MadGraph5.

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