problems with UFO in madgraph

Asked by Emidio Gabrielli on 2021-02-15

I generated a UFO for madgraph using Feynrules. The UFO is related to a new simple Lagrangian containing a scalar interaction with electrons and muons. No error at the Feynrules stage, all is working fine. However when I import the corresponding UFO in Madgraph using the command import UFOnamedirectory,

an error appears only when I am running a process that contains particles and interactions different from the ones defined in the UFO. For the interactions and particles appearing in the UFO, all is OK in madgraph.

Although, in madgraph the SM particle seems to be recognized, if I try for example to generate a simple SM process it gives me the following error (while it works fine for processes generated by the imported UFO lagrangian), notice that tau is not appearing in the new lagrangian

generate e+ e- > tau+ tau -

the output in ""

"Command "generate e+ e- > ta+ ta-" interrupted with error:
NoDiagramException : No amplitudes generated from process Process: e+ e- > ta+ ta- WEIGHTED=4 @1. Please enter a valid process"

Any idea where the error could be ?

I run madgraph using python2.7 in ubuntu.

Thanks in advance for your help.

Best regards, Emidio Gabrielli

Question information

Language:
English Edit question
Status:
Answered
For:
MadGraph5_aMC@NLO Edit question
Assignee:
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Last query:
2021-02-15
Last reply:
2021-02-15

Hi,

The issue is likely in the UFO model and therefore not sure what I can do for you.

My advise would be to do
display vertices e+ e-
and
display vertices ta+ ta-

to check if you have the interactions that you think about.
I guess that the issue is that you do not have e+ e- a vertex and/or ta+ ta- a vertex

Cheers,

Oliver

> On 15 Feb 2021, at 11:41, Emidio Gabrielli <email address hidden> wrote:
>
> New question #695544 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/695544
>
> I generated a UFO for madgraph using Feynrules. The UFO is related to a new simple Lagrangian containing a scalar interaction with electrons and muons. No error at the Feynrules stage, all is working fine. However when I import the corresponding UFO in Madgraph using the command import UFOnamedirectory,
>
> an error appears only when I am running a process that contains particles and interactions different from the ones defined in the UFO. For the interactions and particles appearing in the UFO, all is OK in madgraph.
>
> Although, in madgraph the SM particle seems to be recognized, if I try for example to generate a simple SM process it gives me the following error (while it works fine for processes generated by the imported UFO lagrangian), notice that tau is not appearing in the new lagrangian
>
> generate e+ e- > tau+ tau -
>
> the output in ""
>
> "Command "generate e+ e- > ta+ ta-" interrupted with error:
> NoDiagramException : No amplitudes generated from process Process: e+ e- > ta+ ta- WEIGHTED=4 @1. Please enter a valid process"
>
> Any idea where the error could be ?
>
> I run madgraph using python2.7 in ubuntu.
>
> Thanks in advance for your help.
>
> Best regards, Emidio Gabrielli
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

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