CalcHEP

the photon emitted by the partons

Asked by Ribella

Hi,

We calculate the process gam gam - > W+, W- at the LHC Here, gam is the photon emitted by proton. We want to add the effect of photons emitted by the partons to this process.
Can I take into account photons emitted by the partons in CalcHep?
Murat

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Alexander Pukhov (pukhov) said : 		#1

On 24.01.2019 19:13, Murat wrote:
> New question #678065 on CalcHEP:
> https://answers.launchpad.net/calchep/+question/678065
>
> Hi,
>
> We calculate the process gam gam - > W+, W- at the LHC Here, gam is the photon emitted by proton. We want to add the effect of photons emitted by the partons to this process.
> Can I take into account photons emitted by the partons in CalcHep?
> Murat
>
 I am not sure that I know correct answer on your question.

For gamma emitted by proton  which is saved  after collision you can use
Proton.Photon  structure function implemented in CalcHEP.

For processes  which destroy proton, but Q^2 is not large one should
use  QCD structure  function with photon component. CalcHEP PDT family
contains

  MRST2004qed_proton  or   NNPDF_lo_as_0130_qed.   You also can link
LHAPDF library and use any   structure function whose name contains "qed".

For processes with jet production you have to use u,U->W+,W-,u,U  and
delete diagrams with A<2, u.   Really I do not know how to organize
matching betweem second and third cases.

Best

     Alexander Pukhov

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Ribella (ribella) said : 		#2

Hi Pukhov,

Thank you for your respeonse. I need a little more research.

Murat