# form factor not having implicit type

Asked by Yong Du on 2019-11-08

Hi,

I'm using the UFO method to define the form factor. I followed the instruction here

Everything goes quite well until when I'm generating events and gFORTRAN complains that "Error: Symbol ‘mdl_ggfac’ at (1) has no IMPLICIT type", where "mdl_ggfac" is my form factor. I looked into the Source/DHELAS directory and it turns out that my definition for the form factor somehow did not get recognized by DHELAS--My definition of the form factor can not even be found in the Source/MODEL. Any suggestions? (I'm using MadGraph v2.3.3)

I do have the "import form_factors as ForFac" at the beginning of my lorentz.py file.

Thanks!
Yong

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Yong Du
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2019-11-10
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2019-11-10
2019-11-09
 Olivier Mattelaer (olivier-mattelaer) said on 2019-11-09: #1

My suggestion would be to test with 2.6.7.
If this does not work with that version, then could you send me your model?

Cheers,

Olivier

> On 8 Nov 2019, at 15:52, Yong Du <email address hidden> wrote:
>
> Question #685702 on MadGraph5_aMC@NLO changed:
>
> Description changed to:
> Hi,
>
> I'm using the UFO method to define the form factor. I followed the
> instruction here
>
>
> Everything goes quite well until when I'm generating events and gFORTRAN
> complains that "Error: Symbol ‘mdl_ggfac’ at (1) has no IMPLICIT type",
> where "mdl_ggfac" is my form factor. I looked into the Source/DHELAS
> directory and it turns out that my definition for the form factor
> somehow did not get recognized by DHELAS--My definition of the form
> factor can not even be found in the Source/MODEL. Any suggestions? (I'm
>
> I do have the "import form_factors as ForFac" at the beginning of my
> lorentz.py file.
>
> Thanks!
> Yong
>
> --

 Yong Du (fallive) said on 2019-11-10: #2

Based on Olivier's check, it turns out to be ALOHA did not recognize my definition for the form factor, so we have to extend the function library and then define our form factor to match our definition in the function library.

On the other hand, for future reader's reference, the hard coded way would be you can revise the fortran files directly generated by ALOHA under Source/DHELAS.

Thank Olivier again for his help!

Yong