MadGraph5_aMC@NLO

how to use photon from parton option in the run_card

Asked by Arka Santra

Hello,
  I want to generate monopoles from the fusion of photon beams. To do that, I need to select three cases in the run card:

  1. Both the photons are from protons (elastic process )
  2. One of the photons is from a proton, other one is from a parton (semi-elastic process)
  3. Both the photons are from partons (inelastic process)

In the run card, I can use the beam option 2 (photon from proton) to get the case 1. But how can I achieve the simulation of case 2 and case 3? Is there any way I can simulate those cases in MadGraph5?

  Thank you very much,
  Arka

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Olivier Mattelaer (olivier-mattelaer) said : 		#1

Dear Arka,

Sorry for the late answer, somehow I missed your question.
This is actually a complicated question on which I do not have the full answer.
In principle to have inelastic photon, you just have to keep the beam option to "1" and use a pdf set containing the inelastic photon.
However you need to be careful since some PDF fit also provides simultaneously the elastic component (NNPDF collaboration for example). With such PDF set you can only have the sum of the three contribution and not separate each contribution.

Cheers,

Olivier

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Arka Santra (santra-arka) said : 		#2

Hi Olivier,
  Thank you for the answer.
  I have a follow up question. If I use LUXqed pdf, will I get only inelastic component if I use beam option to 1? Do you recommend any other pdf set for calculating the inelastic component?

  Thank you,
  Arka

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Olivier Mattelaer (olivier-mattelaer) said : 		#3

Dear Arka,

I would suggest you to read: https://arxiv.org/pdf/1607.04266.pdf
Which details the LUXqed pdf.
After reading that paper, it should be clear what they choose to include.
I have taken a quick look into it, and in particular to figure 2 which seems to indicate that they include both the elastic and inelastic component.
But I strongly suggest that you read the full paper to be 100% sure.

Cheers,

Olivier

On 11 Jul 2017, at 13:44, Arka Santra <<email address hidden><mailto:<email address hidden>>> wrote:

Question #645163 on MadGraph5_aMC@NLO changed:
https://answers.launchpad.net/mg5amcnlo/+question/645163

   Status: Answered => Open

Arka Santra is still having a problem:
Hi Olivier,
 Thank you for the answer.
 I have a follow up question. If I use LUXqed pdf, will I get only inelastic component if I use beam option to 1? Do you recommend any other pdf set for calculating the inelastic component?

 Thank you,
 Arka

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