[[snowmass2013:montecarlo| <<back]]

==== 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  [[https://herwig.hepforge.org/|HERWIG++]] model,
and processed using the [[https://cp3.irmp.ucl.ac.be/projects/delphes | Delphes 3.05]] fast detector simulation.

All data  are stored in the  ROOT format  using the standard [[https://cp3.irmp.ucl.ac.be/projects/delphes | Delphes 3.05]] output.
Therefore, it is recommended to install [[https://cp3.irmp.ucl.ac.be/projects/delphes | 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 ====

Please read the Section [[snowmass2013:download| 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:
<code>
g g -> t tbar
q qbar -> t tbar
</code>


Here is the log file for 200 events (one ROOT file).
<hidden>
<code>
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
==============================================================================

</code>
</hidden>


If you need complete log files for a single ROOT file, take it from 

  - [[http://mc.hep.anl.gov/asc/snowmass2013/delphes3/ttbar/LHC_signal.log.gz | LHC_signal.log.gz]] HERWIG++ log file
  - [[http://mc.hep.anl.gov/asc/snowmass2013/delphes3/ttbar/Analysis.log.gz | Analysis.log.gz]] Delphes3 log file


Get the Delphes3 ROOT files from  [[http://mc.hep.anl.gov/asc/snowmass2013/delphes3/ttbar/signal | 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: 
<code>
python download.py 5  delphes3/ttbar/signal  herwigpp_ttbar_sig
</code>
(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)).
<hidden>
<code>
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
==============================================================================
</code>
</hidden>

If you need complete log file for a single ROOT file, take it from 

  * [[http://mc.hep.anl.gov/asc/snowmass2013/delphes3/ttbar/LHC_pileup.log.gz | LHC_pileup.log.gz]] HERWIG++ log file
  * [[http://mc.hep.anl.gov/asc/snowmass2013/delphes3/ttbar/Analysis.log.gz | Analysis.log.gz]] Delphes3 log file


Get the ROOT files grouped from  [[http://mc.hep.anl.gov/asc/snowmass2013/delphes3/ttbar/mu50/signal_pileup | 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:

<code bash>
herwigpp_ttbar_sig_[N].root (signal) corresponds herwigpp_ttbar_sig_50mu_[N].root (signal+50 pileups)
</code>  
where [N] is a number from 1- 96.

Here is an example for downloading 5 files: 
<code>
python download.py 5 delphes3/ttbar/mu50/signal_pileup  herwigpp_ttbar_sig_50mu
</code>

==== Only pile up events without the signal  ====

Here are pileup events used to mix with the signal events
Look at the  [[http://mc.hep.anl.gov/asc/snowmass2013/delphes3/ttbar/mu50/pileup | this  download link]]

<code>
python download.py 5 delphes3/ttbar/mu50/pileup  herwigpp_pileup50f
</code>


==== Info about true particle record ====


To reduce ROOT file size, truth information in these ROOT files was slimmed. Please read [[snowmass2013:pileup_truth_d3| 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 [[snowmass2013:analyse_d3]]



 --- //[[chekanov@anl.gov|Sergei Chekanov]] 2013/03/06 20:47//