MadGraph5_aMC@NLO

Set rapidity cut for Z boson

Asked by rbalgc

Dear all,

I'm trying to apply a cut on the rapidity of the Z boson in a pp>tt~z process. I'm using MG3.1.1 and I've tried to add such cut in the file SubProcesses/cuts.f, where I've added (just below the example) the code:

C Cut on Z boson rapidity
      do i=1,nexternal ! loop over all external particles
         if (istatus(i).eq.1 ! final state particle
     & .and. abs(ipdg(i)).eq.22) then ! Z boson
C apply the y cut (abs(y) should be lower than 2 for the event to
C pass cuts)
            if ( abs(rap2(p(0:3,i))) .gt. 2 ) then
C momenta do not pass cuts. Set passcuts_user to false and return
               passcuts_user=.false.
               return
            endif
         endif
      enddo

But computing the cross-section via ./bin/aMCatNLO launch LO I obtain no difference with and without the cut.
Should I implement the cut somewhere else? Or do I need to change other files for it to apply?

Thank you

Question information

Language:
English Edit question
Status:
Solved
For:
MadGraph5_aMC@NLO Edit question
Assignee:
No assignee Edit question
Solved by:
Olivier Mattelaer
Solved:
Last query:
Last reply:
Revision history for this message
Best Olivier Mattelaer (olivier-mattelaer) said : 		#1

Hi,

22 is the pdg code for the photon. So I guess that this is your issue.

Cheers,

Olivier

> On 29 Jul 2021, at 16:20, rbalgc <email address hidden> wrote:
>
> New question #698191 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/698191
>
> Dear all,
>
> I'm trying to apply a cut on the rapidity of the Z boson in a pp>tt~z process. I'm using MG3.1.1 and I've tried to add such cut in the file SubProcesses/cuts.f, where I've added (just below the example) the code:
>
> C Cut on Z boson rapidity
> do i=1,nexternal ! loop over all external particles
> if (istatus(i).eq.1 ! final state particle
> & .and. abs(ipdg(i)).eq.22) then ! Z boson
> C apply the y cut (abs(y) should be lower than 2 for the event to
> C pass cuts)
> if ( abs(rap2(p(0:3,i))) .gt. 2 ) then
> C momenta do not pass cuts. Set passcuts_user to false and return
> passcuts_user=.false.
> return
> endif
> endif
> enddo
>
> But computing the cross-section via ./bin/aMCatNLO launch LO I obtain no difference with and without the cut.
> Should I implement the cut somewhere else? Or do I need to change other files for it to apply?
>
> Thank you
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

Revision history for this message
rbalgc (rbalgc) said : 		#2

Thanks Olivier Mattelaer, that solved my question.