renormalization and factorization scales equal to photon transverse energy

Asked by amir on 2019-08-27

Hello madgraph developers

I wanted to generate a p p > a j [QCD] process with renormalization and factorization scales equal to photon transverse energy in a certain bin. may I ask if is it ok to set dynamical scale choice inside run card to 1 or should I use further line of hard code inside set scale.f file?:

         tmp=0d0
         do i=3,nexternal
            if((pp(0,i)+pp(3,i))*(pp(0,i)-pp(3,i)).eq.0d0) then
                tmp=tmp+et(pp(0,i))
            else
                tmp = tmp + 0d0
            endif
         enddo
         temp_scale_id='User-defined dynamical scale' ! use a meaningful string

if is it incorrect would you mind to help me on this?

cheers,
Amir

Question information

Language:
English Edit question
Status:
Solved
For:
MadGraph5_aMC@NLO Edit question
Assignee:
Rikkert Frederix Edit question
Solved by:
Rikkert Frederix
Solved:
2019-08-28
Last query:
2019-08-28
Last reply:
2019-08-28
Best Rikkert Frederix (frederix) said : #1

Dear Amir,

The momenta in the 'scale_global_reference' function are the momenta as they enter the respective matrix elements. For the pp>aj[QCD] process the 3rd momentum is the momentum of the photon. Hence, setting the scale to

sqrt(pp(1,3)**2+pp(2,3)**2)

sets it to the transverse momentum of the photon.

Best regards,
Rikkert

amir (amir-shabanpoor92) said : #2

Dear Rikkert

Thank you very much for your help and support

Cheers,
Amir

On Wed, Aug 28, 2019, 11:12 PM Rikkert Frederix <
<email address hidden>> wrote:

> Your question #683394 on MadGraph5_aMC@NLO changed:
> https://answers.launchpad.net/mg5amcnlo/+question/683394
>
> Status: Open => Answered
>
> Rikkert Frederix proposed the following answer:
> Dear Amir,
>
> The momenta in the 'scale_global_reference' function are the momenta as
> they enter the respective matrix elements. For the pp>aj[QCD] process
> the 3rd momentum is the momentum of the photon. Hence, setting the scale
> to
>
> sqrt(pp(1,3)**2+pp(2,3)**2)
>
> sets it to the transverse momentum of the photon.
>
> Best regards,
> Rikkert
>
> --
> If this answers your question, please go to the following page to let us
> know that it is solved:
>
> https://answers.launchpad.net/mg5amcnlo/+question/683394/+confirm?answer_id=0
>
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> following page to enter your feedback:
> https://answers.launchpad.net/mg5amcnlo/+question/683394
>
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>

amir (amir-shabanpoor92) said : #3

Thanks Rikkert Frederix, that solved my question.