MadGraph5_aMC@NLO

PDF =2 in Mad5

Asked by Heng-Yu Chen

Dear Sir :
Sorry for keeping bothering you.
The processes I am working on all involve neutrino scattering from photons.
I used madgraph to check ve a -> e- w+. Now I am looking at ve p > p e- w+. eventually, I will look at ve + iron -> iron e- w+.
But for now, the process I am working is ve p > p e- w+.
I use proton as a target but not try to probe the inner structure of proton
I want to understand how ve interacting with the Coulomb's field of proton.
That is why I am asking the definition of "PDF = 2 (2=photon from proton)" in mad 5
and want to know whether they relate to the form factor of the proton or not.
It seems there is no clear definition of "PDF =2 in Mad5" in the user manual or on the internet.

I use the website to generate the code for ve p > p e- w+.
It shows me all the diagrams for the interactions between ve and up, down quarks.
The only thing I know I can control is pp1 (nu), lpp2 (proton) and the line 'cteq6l1' = pdlabel.
I know, at proton level, somehow the PDF and form factor of proton are related.
But I am not sure when I set lpp2 (proton) to 1, does it also mean I have decided the form factor of proton?
Or should I set lpp2 to 2 (2=photon from proton)? Can I say lpp2=2 control the form factor of proton?
Moreover, photon is virtual in this process. Could I just set lpp2=2 directly?
Or should I import a new model for this process?
I really appreciate your patience answering my question.

Best!

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Olivier Mattelaer (olivier-mattelaer) said : 		#1

Hi,

Still not sure to understand what you want.
so do you want the a ve > e- w+
with the photon coming from the proton?
This would be the correct syntax to use PDF=2

This is the paper that we follow for pdf=2:
http://arxiv.org/abs/hep-ph/9310350
you will have more information on the following two questions:
https://answers.launchpad.net/madgraph5/+question/228668
https://answers.launchpad.net/madgraph5/+question/224904

If you need to implement your own functions, you can modify the current one by modifying the following file:
Source/PDF/PhotonFlux.f

Cheers,

Olivier

On Dec 16, 2013, at 8:06 PM, Heng-Yu Chen <email address hidden> wrote:

> New question #240880 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/madgraph5/+question/240880
>
> Dear Sir :
> Sorry for keeping bothering you.
> The processes I am working on all involve neutrino scattering from photons.
> I used madgraph to check ve a -> e- w+. Now I am looking at ve p > p e- w+. eventually, I will look at ve + iron -> iron e- w+.
> But for now, the process I am working is ve p > p e- w+.
> I use proton as a target but not try to probe the inner structure of proton
> I want to understand how ve interacting with the Coulomb's field of proton.
> That is why I am asking the definition of "PDF = 2 (2=photon from proton)" in mad 5
> and want to know whether they relate to the form factor of the proton or not.
> It seems there is no clear definition of "PDF =2 in Mad5" in the user manual or on the internet.
>
> I use the website to generate the code for ve p > p e- w+.
> It shows me all the diagrams for the interactions between ve and up, down quarks.
> The only thing I know I can control is pp1 (nu), lpp2 (proton) and the line 'cteq6l1' = pdlabel.
> I know, at proton level, somehow the PDF and form factor of proton are related.
> But I am not sure when I set lpp2 (proton) to 1, does it also mean I have decided the form factor of proton?
> Or should I set lpp2 to 2 (2=photon from proton)? Can I say lpp2=2 control the form factor of proton?
> Moreover, photon is virtual in this process. Could I just set lpp2=2 directly?
> Or should I import a new model for this process?
> I really appreciate your patience answering my question.
>
> Best!
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

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