matching in decays with large pt cut
Hi,
I’m interested in boosted fat jet, like in the p p > z z , z > vl vl~, z > j j process. I assume the two jets from Z boson could further be clustered by FastJet to form a fat jet. Since I want to pick out those events with boosted Z, I prefer to use a jet pt cut by setting a large value to htjmin in run_card.
The script I used is
generate p p > z z , z > vl vl~ , z > j j
add process p p > z z , z > vl vl~ , z > j j j
output jet/DJR
launch
shower=PYTHIA8
set ebeam1 7000
set ebeam2 7000
set ickkw 1
set auto_ptj_mjj True
set xqcut 20
set cut_decays True
set htjmin 400
set JetMatching:qCut 30
set JetMatching:nJetMax 3
set Merging:nJetMax 3
with other cuts at default values.
The cut_cecays=TRUE means htjmin cut is now on the jets from Z decay. However I don’t want to lose the phase space between the xqcut (and also Qcut) scale and the htjmin scale, so I added the process where the Z boson decays to three jets for a simple test.
After parton shower with pythia8 installed with Madgraph_v2_5_5, I checked the DJR plots but there’s no information about the contribution from 0-jet sample ,1-jet sample...
Now I’m not sure if this is the right way to generate events with large jet pt cut and proper matching. Can you help me with this problem?
1. Is it possible to do matching for the process I chose, as the jets are form an on-shell decay? According to https:/
2. What Qcut value should I choose if I already used some large ptj or htjmin cut, in order not to loose the phase space that should be filled by pythia? If the value should be choose to be 1/3~1/6 the hard scale, should I use htjmin*1/6 instead? But to my understanding, Qcut is the scale in parton shower, which is for low scale radiation, is it still valid when i choose some high scale value like 200 GeV?
Thanks a lot!
Tao Xu
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