Pseudorapidity cut of charged leptons

Asked by Özer Özdal on 2020-06-18

Dear experts,

I would like to apply a pseudorapidity cut only for positively (or negatively) charged leptons instead of the standard absolute-rapidity cuts given in the run_card.dat. I have added the following lines into cuts.f file, and commented out the other (pseudo-)rapidity-related cuts in the code. How can I check on the pdg code of the object in order to restrain only the pseudorapidity of the electron (or the positron), and not the one of all leptons ? Thanks.

c Cut on Eta for charged leptons
      do i=nincoming+1,nexternal
        if(is_a_l(i))then
                if (rap(p(0,i)).lt.0) then ! (Select Eta > 0)
                        passcuts=.false.
                        return
                endif
        endif
      end do

Cheers,
Özer

Question information

Language:
English Edit question
Status:
Answered
For:
MadGraph5_aMC@NLO Edit question
Assignee:
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Last query:
2020-06-18
Last reply:
2020-06-18

Hi,

You have to understand that such cut is not to always going to work. The reason is that madgraph use a lot of optimization to speed up the computation and that your cut is not compatible with such optimization.
They are two optimization that you have to ask madgraph to not use:
1) beam symmetry (u u~ process is the same as u~ u)
2) lepton symmetry (optimization e- and mu-)

To remove the first and at least partly the second, you have to generate the code sith
set group_subprocesses False
Depending of your process, madgraph might still use some optimization on lepton. In that case you also need to ensure that at least the muon is massive.

After all that, you should be able to distinguish electron for muon,
At that stage the easiest is to have a different file dummy_fct.f for the directory with electron and muon.

Otherwise, you have to split the is_a_l option in two sub-gategory (but this can means change plenty of files).

Cheers,

Olivier

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