Jet multiplicity problem

Asked by Jose on 2017-07-25

Hi everybody, I am having some troubles when I try to analyze the output from this code. I am simulating a proton-proton collision to produce a pair of top quarks, these quarks decay as specified below. The generation of events is not a problem, the problem begins when Pythia8 starts the showering processes ( I think ).

I analyze the output file from pyhia (lhe file) with MadAnalysis5, when I ask for the number of jets (hard and soft jets) the program tells me that there are exactly 4 jets, which correspond to the 4 jet final state of the hard scattering, and no more jets.

I don't know why my simulations can't generate more jets. Looking for some information Pythia usually adds more jets to the showering and in some examples on the internet some people programs 2 jets at the final state in madgraph and the analysis shows up to 8 jets after showering with pythia.

Any idea of this behaviour? Maybe there are some missing variables in the code.

Thanks in advance.

######################################################################
#import model sm
define q = u d c s u~ d~ c~ s~
generate p p > t t~
output pptt~_LO_SM
#######################################################################
set automatic_html_opening False
launch pptt~_LO_SM

shower=PYTHIA8
analysis=OFF
madspin=ON

set run_card nevents 15000
set ebeam1 7000
set ebeam2 7000

set ickkw 1
set xqcut 20
set drjj 0
set etaj 5
set ptj 0
set auto_ptj_mjj False

set pythia8_card JetMatching:qCut 30
set JetMatching:nJetMax 8
set maxjetflavor = 5

decay t > w+ b, w+ > l+ vl
decay t~ > w- b~, w- > q q

done
#######################################################################

Question information

Language:
English Edit question
Status:
Answered
For:
MadGraph5_aMC@NLO Edit question
Assignee:
No assignee Edit question
Last query:
2017-07-25
Last reply:
2017-07-25

Hi,

The the is the input to pythia8 not the output.

Cheers,

Olivier

> On 25 Jul 2017, at 10:59, Jose <email address hidden> wrote:
>
> New question #652974 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/652974
>
> Hi everybody, I am having some troubles when I try to analyze the output from this code. I am simulating a proton-proton collision to produce a pair of top quarks, these quarks decay as specified below. The generation of events is not a problem, the problem begins when Pythia8 starts the showering processes ( I think ).
>
> I analyze the output file from pyhia (lhe file) with MadAnalysis5, when I ask for the number of jets (hard and soft jets) the program tells me that there are exactly 4 jets, which correspond to the 4 jet final state of the hard scattering, and no more jets.
>
> I don't know why my simulations can't generate more jets. Looking for some information Pythia usually adds more jets to the showering and in some examples on the internet some people programs 2 jets at the final state in madgraph and the analysis shows up to 8 jets after showering with pythia.
>
> Any idea of this behaviour? Maybe there are some missing variables in the code.
>
> Thanks in advance.
>
> ######################################################################
> #import model sm
> define q = u d c s u~ d~ c~ s~
> generate p p > t t~
> output pptt~_LO_SM
> #######################################################################
> set automatic_html_opening False
> launch pptt~_LO_SM
>
> shower=PYTHIA8
> analysis=OFF
> madspin=ON
>
> set run_card nevents 15000
> set ebeam1 7000
> set ebeam2 7000
>
> set ickkw 1
> set xqcut 20
> set drjj 0
> set etaj 5
> set ptj 0
> set auto_ptj_mjj False
>
> set pythia8_card JetMatching:qCut 30
> set JetMatching:nJetMax 8
> set maxjetflavor = 5
>
> decay t > w+ b, w+ > l+ vl
> decay t~ > w- b~, w- > q q
>
> done
> #######################################################################
>
>
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

Jose (joseantoniovictoria) said : #2

Hi,

I thought that when you link pythia and madgraph the LHE file includes the hard scattering process plus the parton shower, hadronization and merging. The program performs a simplification of the HepMC file, thats why I am opening this file.

I also have an HepMC file, maybe I should work with this but this is not the procedure I saw on some tutorials.

Thanks for the helps.

Jose

Yes the hempc is the file that you are looking for to have the events after the parton shower.

Cheers,

Olivier

> On 25 Jul 2017, at 15:53, Jose <email address hidden> wrote:
>
> Question #652974 on MadGraph5_aMC@NLO changed:
> https://answers.launchpad.net/mg5amcnlo/+question/652974
>
> Status: Answered => Open
>
> Jose is still having a problem:
> Hi,
>
> I thought that when you link pythia and madgraph the LHE file includes
> the hard scattering process plus the parton shower, hadronization and
> merging. The program performs a simplification of the HepMC file, thats
> why I am opening this file.
>
> I also have an HepMC file, maybe I should work with this but this is not
> the procedure I saw on some tutorials.
>
> Thanks for the helps.
>
> Jose
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

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