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Low-pT ttbar with pileup
Here are the links to the existing Monte Carlo samples for top-quark studies generated for the 14 TeV center-of-mass energy (pp collisions). Events were generated with the HERWIG++ model,
and processed using the Delphes 3.05 fast detector simulation.
All data are stored in the ROOT format using the standard Delphes 3.05 output.
Therefore, it is recommended to install Delphes 3.0.5 and look at the example
explaining how to read such ROOT files (see the directory “Examples” inside the Delphes package).
The samples use the ATLAS detector geometry located in “examples/delphes_card_ATLAS.tcl” of the Delphes 3.05 installation.
There is only one difference: Jets are reconstructed using AntiKT jets with the cone 0.5.
How to download
Signal ttbar
This is a ttbar fully inclusive sample without any cut on hard processes and without pileup. As before, sqrt(s)=14 TeV, The included processes are:
g g -> t tbar
q qbar -> t tbar
Here is the log file for 200 events (one ROOT file).
Statistics for the UE process:
generated number of Cross-section
events attempts (nb)
==============================================================================
Total: 102341 102341 2.31448e+08
==============================================================================
Per matrix element breakdown:
MEQCD2to2Fast 102341 102341 2.31448e+08
==============================================================================
==============================================================================
Eikonalized and soft cross sections:
Model parameters: ptmin: 3.5973 GeV, mu2: 0.81 GeV2
DL mode: 2, CMenergy: 14000 GeV
hard inclusive cross section (mb): 231.488
soft inclusive cross section (mb): 27.1639
total cross section (mb): 113.95
inelastic cross section (mb): 78.5382
soft inv radius (GeV2): 0.304411
slope of soft pt spectrum (1/GeV2): -0.901857
Average hard multiplicity: 5.47435
Average soft multiplicity: 0.359462
==============================================================================
==============================================================================
Statistics for event handler 'LHCHandler':
generated number of Cross-section
events attempts (nb)
==============================================================================
Total (from weighted events): including vetoed events 0.62(2)e+00
==============================================================================
Total (from unweighted events): 200 200 0.62(5)e+00
==============================================================================
Per matrix element breakdown:
MEHeavyQuark 200 200 0.62(5)e+00
==============================================================================
If you need complete log files for a single ROOT file, take it from
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Get the Delphes3 ROOT files from this download link
In total, there are 96 files, with 200 ttbar events in each. Thus the total number of events is 19200 signal events. The total luminosity is 31 pb-1
Here is an example for downloading 5 files:
python download.py 5 delphes3/ttbar/signal herwigpp_ttbar_sig
(set 5 to 96 to download all)
Signal plus pileup
The truth information from the signal MC shown above was used to overlay with 140 pile up events (fixed number, not “Poisson” case!)
The events were overplayed at the HEPMC true level (thanks to Andy Buckley for his help and http://pilemc.hepforge.org/ tool), and then were processed using Delphes3.04
(thanks to Dephes3 team which helped to solve technical issues).
Here is the log file for 11000 UE events (which were used as a pool of events for 200 signal events)).
Statistics for the UE process:
generated number of Cross-section
events attempts (nb)
==============================================================================
Total: 248527 248527 2.31723e+08
==============================================================================
Per matrix element breakdown:
MEQCD2to2Fast 248527 248527 2.31723e+08
==============================================================================
==============================================================================
Eikonalized and soft cross sections:
Model parameters: ptmin: 3.5973 GeV, mu2: 1.11 GeV2
DL mode: 2, CMenergy: 14000 GeV
hard inclusive cross section (mb): 231.454
soft inclusive cross section (mb): 68.5499
total cross section (mb): 113.95
inelastic cross section (mb): 77.963
soft inv radius (GeV2): 0.382009
slope of soft pt spectrum (1/GeV2): -0.338063
Average hard multiplicity: 2.96865
Average soft multiplicity: 0.871836
==============================================================================
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>> ThePEG - Toolkit for HEP Event Generation - version 1.8.1 <<<<<<<<<<
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
==============================================================================
Statistics for event handler 'LHCHandler':
generated number of Cross-section
events attempts (nb)
==============================================================================
Total (from weighted events): including vetoed events 84.6(3)e+00
==============================================================================
Total (from unweighted events): 30000 38053 66.7(5)e+00
==============================================================================
Per matrix element breakdown:
MEMinBias 30000 38053 66.7(5)e+00
==============================================================================
If you need complete log file for a single ROOT file, take it from
Get the ROOT files grouped from this download link
In total, there are 96 files, with 200 ttbar events in each. Thus the total number of events is 19200 signal events. The total size of the files is 48 GB.
Each file corresponds exactly to the signal file. For example:
herwigpp_ttbar_sig_[N].root (signal) corresponds herwigpp_ttbar_sig_50mu_[N].root (signal+50 pileups)
where [N] is a number from 1- 96.
Here is an example for downloading 5 files:
python download.py 5 delphes3/ttbar/mu50/signal_pileup herwigpp_ttbar_sig_50mu
Only pile up events without the signal
Here are pileup events used to mix with the signal events
Look at the this download link
python download.py 5 delphes3/ttbar/mu50/pileup herwigpp_pileup50f
Info about true particle record
To reduce ROOT file size, truth information in these ROOT files was slimmed. Please read here.
How to analyze
If you need to find the effect of pileup on top reconstruction or a jet measurement, you need to run the analysis code over signal MC and then over the signal+pileup MC files.
Read analyse_d3
— Sergei Chekanov 2013/03/06 20:47