-- SebastianOlivares - 2015-09-15


Event Generation

The generator choosen for this analysis is the latest version of JHU (http://www.pha.jhu.edu/spin/).


After downloading and compiling the latest version of JHU (v5.6.3 in our case), you need to modify the file JHUGenerator/mod_Parameters.F90 according to the following models:

Model Production couplings Decay couplings Decay helicity amplitudes Comments
0^- g_4=1 g_4=1 f_{++}=f_{--}=0.5 ZZ->2l2q
2^+_b g_1=1: gg,qq g_5=1 f_{00}=0.98 VV->4q, ZZ->2l2q
2^+_m g_1=1: gg,qq g_1=g_5=1 f_{00}=0.08,f_{+-}=f_{-+}=0.46 VV->4q
2^+_t g_1=1: gg,qq g_1=1 f_{+-}=f_{-+}=0.5 ZZ->2l2q
2^+_{h1} g_1=1: gg,qq g_8=1 f_{+-}=f_{-+}=0.5 VV->4q, ZZ->2l2q
2^+_{h2} qq g_9=1 f_{+0}=f_{0+}=f_{-0}=f_{0-}=0.25 VV->4q, ZZ->2l2q

Please remember that you need to change the center mass energy (LHC_Energy=13000d0). After compiling the package with the corresponding parameters for each model, you can generate the sample using something similar to the following example (RS Graviton, gg, 30000 events).

 ./JHUGen Collider=1 Process=2 PChannel=0 VegasNc2=30000 DecayMode1=1 DecayMode2=1 DataFile=Graviton_RS_ZZ4q_gg_m2000

Some of the parameters are:

  • Collider (int): Type of collider (1=LHC)
  • Process (int): Spin of the particle (0=spin0, 2=spin2).
  • PChannel (int): Production channel (0=gg, 1=qqbar, 2=both).
  • VegasNc2 (int): Number of events for the output file (we are using 30k).
  • DecayMode1 (int): Decay mode of the first boson (0=Z->2q, 5=W->2q)
  • DecayMode2 (int): Decay mode of the second boson (0=Z->2q, 5=W->2q)
  • DataFile (string): Name of the output LHE file.

Some JHU event samples are in:


Kinematic variables



The hadronization is done using ATLAS MC15 configuration with Pythia8 (more details: https://twiki.cern.ch/twiki/bin/viewauth/AtlasProtected/AtlasMcProductionMC15).

Setup and input file preparation

First you need to setup MC15 according to the latest validation release (https://svnweb.cern.ch/trac/atlasoff/browser/Generators/MC15JobOptions/trunk/common/Latest_caches.txt, http://atlas-computing.web.cern.ch/atlas-computing/projects/releases/status/). In our case we did:

export ATLAS_LOCAL_ROOT_BASE=/cvmfs/atlas.cern.ch/repo/ATLASLocalRootBase
source ${ATLAS_LOCAL_ROOT_BASE}/user/atlasLocalSetup.sh

The input files for the hadronization process are the LHE (Les Houches) samples created in the previous step with JHU. However, you need to rename and compress the files in order to be used by the event generator (more details in https://twiki.cern.ch/twiki/bin/viewauth/AtlasProtected/PreparingLesHouchesEven#Make_the_events). For example:

mv Graviton_RS_ZZ4q_qqbar_m2000.lhe group.phys-gener.JHUPythia8_CTEQ6L1.429110.qqbar_RSGraviton_ZZ4q.13TeV.TXT.mc15_v1._00001.events
mv Graviton_RS_ZZ4q_qqbar_m2000.dat group.phys-gener.JHUPythia8_CTEQ6L1.429110.qqbar_RSGraviton_ZZ4q.13TeV.TXT.mc15_v1._00001.dat
tar -cvzf group.phys-gener.JHUPythia8_CTEQ6L1.429110.qqbar_RSGraviton_ZZ4q.13TeV.TXT.mc15_v1._00001.tar.gz group.phys-gener.JHUPythia8_CTEQ6L1.429110.qqbar_RSGraviton_ZZ4q.13TeV.TXT.mc15_v1._00001.events group.phys-gener.JHUPythia8_CTEQ6L1.429110.qqbar_RSGraviton_ZZ4q.13TeV.TXT.mc15_v1._00001.dat

Configuration files

You should export the following variable in order to access the most recent MC15JobOptions files on cvfms.

export JOBOPTSEARCHPATH=/cvmfs/atlas.cern.ch/repo/sw/Generators/MC15JobOptions/latest/common:$JOBOPTSEARCHPATH

The jobOptions file contains the physics and the configuration setting that is passed to the generator. In our case we follow the jobOptions file from the run1 mc12 Higgs spin analysis (https://svnweb.cern.ch/trac/atlasoff/browser/Generators/MC12JobOptions/trunk/share/DSID181xxx/MC12.181991.PowhegJHUPythia8_CT10_ggH125p5_Spin0m_ZZ4lep.py). There are natural differences; like the PDF choice, MC version, the final simulation of the EM shower (Photos is not implemented in MC15) and the presence of Pythia8_JHU job option. The jobOption file is attached.

Now you can run a MC15 generation script, making sure the setup is in place and the jobOptions are in your test directory. For example:

Generate_tf.py --ecmEnergy=13000 --runNumber=429110 --maxEvents=25000 --jobConfig=/afs/cern.ch/user/s/saolivap/Exotics/MCGenerator/MC15JobOptions/share/DSID429xxx/MC15.429110.JHUPythia8_CTEQ6L1_qqbar_RSGraviton_ZZ4q.py --inputGeneratorFile=/afs/cern.ch/user/s/saolivap/public/Exotics/lhefiles/group.phys-gener.JHUPythia8_CTEQ6L1.429110.qqbar_RSGraviton_ZZ4q.13TeV.TXT.mc15_v1._00001.tar.gz --outputEVNTFile=MC15_429110_qqbar_RSGraviton_ZZ4q.EVNT.pool.root

Some of the parameters are:

  • ecmEnergy (float): Center of mass energy parameter in GeV e.g. 13000 (should coincide with the LHE sample).
  • runNumber (int): Run number of the sample that involved the physics process, should be the same as the jobOption.
  • maxEvents (int) default=-1: Maximum number of events to process.
  • jobConfig (list): jobOptions fragment containing the physics and the configuration settings which is passed to the generators.
  • inputGeneratorFile (list): LHE file that contains the generated events.
  • outputEVNTFile (list): Name of the output file created.

Please take into account that the input file, jobConfig and run number must have a similar name convention, just as is specified in the previous command.

Some hadronized event samples are in:


Truth DAOD

Event generation jobs in ATLAS produce a format called EVNT. Given that this formats cannot easily be read, software has been prepared to convert EVNT into a variety of xAOD formats which can be read with ROOT, and which use the ATLAS analysis EDM (more details: https://twiki.cern.ch/twiki/bin/view/AtlasProtected/TruthDAOD).

Running script

Setup a working release:

asetup 20.1.X.Y-VAL,rel_1,AtlasDerivation,gcc48,here --nightliesarea=/afs/cern.ch/atlas/software/builds/nightlies

Run the script as follows:

Reco_tf.py --inputEVNTFile MC15_429110_Graviton.EVNT.pool.root --outputDAODFile MC15_Graviton.pool.root --reductionConf TRUTH1

The option TRUTH1 is the main format for truth analysis.

Some truth event samples are in:


Major updates:
-- Main.Sebastian Olivares - 15 Sept 2015

RESPONSIBLE SebastianOlivares
REVIEW Never reviewed

Topic attachments
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Texttxt MC15.429110.JHUPythia8_CTEQ6L1_qqbar_RSGraviton_ZZ4q.py.txt r1 manage 0.4 K 2015-09-15 - 19:53 SebastianOlivares jobOption VVJJ Polarization Analysis - JHU+Pythia8
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Topic revision: r2 - 2015-09-22 - SebastianOlivares
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