Z boson + c-jet

Did you read this:

https://answers.launchpad.net/mg5amcnlo/+question/261987

Cheers,

Olivier
On 08 Apr 2015, at 15:16, saeedeh <email address hidden> wrote:

> New question #264822 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/264822
>
> Dear authors,
>
> I'm working on studying the Z Bosons with Charm Quark Jets
> in pp¯ Collision. I'm trying to compare my results with the results of D0 collaboration (arXiv:1308.4384 ).
> So I generate p p > z c [QCD] and use the cut of the above paper. Sine there is no maximum pT for the jet at NLO in the run_card. I coded it in cut.f
> C***************************************************************
> C***************************************************************
> C PUT HERE YOUR USER-DEFINED CUTS
> C***************************************************************
> C***************************************************************
> C
> c$$$C EXAMPLE: cut on top quark pT
> do i=1,nexternal ! loop over all external particles
> if (istatus(i).eq.1 ! final state particle
> & .and. abs(ipdg(i)).eq.4) then ! top quark
> c$$$C apply the pT cut (pT should be large than 200 GeV for the event to
> c$$$C pass cuts)
> if ( p(1,i)**2+p(2,i)**2 .lt. 200.d0**2 ) then
> c$$$C momenta do not pass cuts. Set passcuts_user to false and return
> passcuts_user=.false.
> return
> endif
> endif
> enddo
> c
> return
> end
> But I faced a problem. My results are much less than D0 data, Pythia, Sherpa, and MCFM predictions.
> For example in pT jet 20–30 my result for ratio z+c/z+b is about 1.4 while the D0 data is about
> 3, Pythia ->3, Sherpa and MCFM->2
>
>
> Since I don't know what the problem is, please give me some comments.
> Thanks in advance for your help.
>
> Saeedeh
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

dear Olivier

I read https://answers.launchpad.net/mg5amcnlo/+question/261987
 and done all Your suggestion and comment.
But I get a very small value for the cross section comparing to phytia, SHERPA,….

I want to generate Single Heavy-Quark Jet (c).
According to the article "Associated Production of a Z Boson and a Single Heavy-Quark Jet"
arXiv:hep-ph/0312024, the main process for the production of a Z plus a heavy quark is
the Compton subprocess g+Q > Z +Q.
If I define p = g u u~ d d~ s s~, I don't have the subprocess g+Q > Z +Q.
moreover, Z in association with a charm (c) quark are produced also
through quark-antiuqrks annihilation q q~->Z g->Z c c~ which
dominates at higher photon transverse momenta and when I
define p = g u u~ d d~ s s~ c c~ I don't see this in subprocess folder.
 However, for both ways to make predictions for Z + charm jet
my results are much less than D0 data, Pythia, Sherpa, and MCFM predictions.

Thank you for your consideration

Saeedeh

Dear Saeedeh,

All the answers are already in the

 https://answers.launchpad.net/mg5amcnlo/+question/261987

thread. Please read it carefully and ask more specific questions if there is something not clear.

best regards,
Rikkert