GeneratingMCEventsForH4lAnalysis (abandoned)

This page summarises the steps needed to generate signal and background events needed for the analysis of the Higgs decay into four leptons.

The following icons are used to indicate the completeness of the sections:

  • Red led - not done yet
  • Yellow led - started but not completed
  • Green led - completed

General

The general procedure is to first run the generator as a standalone program to produce a list of events. These events are then the input for Pythia or Herwig to add initial and final state radiation, hadronisation and decays. This second step can be done within the Athena framework, where one can also apply event filters to the output.

H4l Red led

Zbb Yellow led

AcerMC Green led

Running AcerMC Green led

First you need to download the AcerMC source code available here. As an alternative you can also find the code at
/afs/cern.ch/atlas/offline/external/acermc
Change into the main directory of the AcerMC code and type
make demo_py
This will compile the code and produce the executables. For more information have a look at the INSTALL file located in the main directory. Next you need to set the correct run parameters in the steering cards. You can find the cards located in the ./prod/ subdirectory. There are four steering cards in total
acermc.card
run.card
photos.card
tauola.card
In this example you will only need to modify the first two files. Go through the list of parameters and set the values as desired. There is some explanation included in the steering card file for each parameter. Probably the most essential file is the run.card. Here you can set the number of event, the centre-of-mass energy and the process to generate. Be sure you set the parameter ACER (in run.card) to 2 in order to store the events to file. To use the settings as they had been used for the CSC-note samples you can use the following two files: acermc.card, run.card

In order to start the generator simply type
make run_py
in the main directory of the AcerMC code. This will produce two files in the ./prod/ subdirectory:
AcerMC_pXXX_rYYYYYY.inparm
AcerMC_pXXX_rYYYYYY.events
where XXX stands for the process and YYYYYY for the seed of the number generator selected in run.card. The first file contains some information summary including the cross-section. The second file contains the event information. Those two files are now needed in the second step.

Running Pythia Green led

Since we will run Pythia inside Athena, you will first need to set up an Athena environment. The example given here has been tested using release 14.2.23. Next you will need the python script available here, which is a slightly modified version of the script also available on CVS under
atlas/Generators/EvgenJobOptions/share/CSC.005177.AcerMC_Zbb_4l.py
Place it together with the two output files from AcerMC in your directory from which you want to run athena. Pythia expects to find a file called inparmAcerMC.dat in the run directory. So simply create a link to your inparm file
ln -s AcerMC_pXXX_rYYYYYY.inparm inparmAcerMC.dat

Modify the python script according to your needs (number of events, output file name,...) and then type
athena.py CSC.005177.AcerMC_Zbb_4l.py

If everything goes well you will end up with an AOD file of the specified name.

Alpgen Red led

MC@NLO Red led

ZZ Red led

tt Red led


Major updates:
-- PhilippFleischmann - 18 Dec 2008

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Topic revision: r2 - 2011-11-08 - PhilippFleischmann
 
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