[[snowmass2013:montecarlo| <<back]]

==== Low-pT ttbar. Signal and signal+pileup ====


Here are samples of [[https://cp3.irmp.ucl.ac.be/projects/delphes | Delphes 3.08]] events generated for the **14 TeV** center-of-mass energy (pp collisions). The events are generated for 0, 50 and 140 pileup scenarios. All data  are stored in the  ROOT format  using the standard [[https://cp3.irmp.ucl.ac.be/projects/delphes | Delphes]] output.
Therefore, it is recommended to install [[https://cp3.irmp.ucl.ac.be/projects/delphes | Delphes]] and look at the example explaining how to read such ROOT files (see the directory "Examples" inside the Delphes package).
The samples use "Snowmass" detector geometry. Jets were corrected using jet area correction.
See [[http://www.snowmass2013.org/tiki-index.php?page=Energy_Frontier_FastSimulation| this wiki]] for details. 

In total, there are 96 files per sample (<mu>=0,50,140), with 1000 ttbar  events in each. Thus the total number of events is  96000 signal events per sample. 
 
==== How to download ====

Please read the Section [[snowmass2013:download| How to download]]. You will need the "download.py" script posted on that page.

=====  Signal ttbar ====

This is a ttbar (fully inclusive, all decays) without any cut on hard processes. HERWIG++ with sqrt(s)=14 TeV was used. 
The included processes at LO ME are:
<code>
g g -> t tbar
q qbar -> t tbar
</code>

Look at the HERWIG++ [[http://mc.hep.anl.gov/asc/snowmass2013/delphes36/ttbar/log/LHC_signal.log.gz | log file]] used to generate the signal ttbar events. This is [[http://mc.hep.anl.gov/asc/snowmass2013/delphes36/ttbar/log/LHC_signal.in | input settings]]

=====  No  pileup =====

Get the Delphes3 ROOT files from  [[http://mc.hep.anl.gov/asc/snowmass2013/delphes36/?dir=httbar/mu0 | this  download link]].
Here is an example for downloading 5 files: 
<code>
python download.py 5  delphes36/ttbar/mu0  herwigpp_ttbar_delphes306
</code>
(set 5 to 96 to download all)


=====  <mu>=50 =====

Get the Delphes3 ROOT files from  [[http://mc.hep.anl.gov/asc/snowmass2013/delphes36/?dir=httbar/mu50 | this  download link]].
Here is an example for downloading 5 files: 
<code>
python download.py 5  delphes36/ttbar/mu50  herwigpp_ttbar_delphes306_mu50 
</code>
(set 5 to 96 to download all)


===== <mu>=140 =====

Get the Delphes3 ROOT files from  [[http://mc.hep.anl.gov/asc/snowmass2013/delphes36/?dir=httbar/mu140 | this  download link]].
Here is an example for downloading 5 files: 
<code>
python download.py 5  delphes36/ttbar/mu140  herwigpp_ttbar_delphes306_mu140
</code>
(set 5 to 96 to download all)



==== How to analyze using ROOT ====

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]]


==== How to analyze without ROOT ====

In some cases, you may not have ROOT installed to read these Delphes files. In this case, you can use
ROOT files converted to the ProMC format which can be read without ROOT (using C++, Java, Python). Read 
[[snowmass2013:analyse_d36_promc| how to read Delphes3 output without ROOT]].


 --- //[[chekanov@anl.gov|Sergei Chekanov]] 2013/03/06 20:48//