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By Fabio Maltoni, Tim Stelzer and the CP3 development team
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http://madgraph.phys.ucl.ac.be/
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http://madgraph.hep.uiuc.edu/
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http://madgraph.roma2.infn.it/
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Technical Details for Setting Up and Running Gridpacks:
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(see http://cp3wks05.fynu.ucl.ac.be/twiki/bin/view/Library/GridDevelopment)
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in the run_card.dat will generate a gridpack.tar.gz. Online, the
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results page will have a link to this package.
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The gridpackage is meant to be sent over to the cluster or grid
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nodes. It's completely frozen, meaning that you cannot change any
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parameters or run options, apart from the # of event and the rnd
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When you unpack it you get:
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The first is a script which accepts two numbers (the number of events
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There are two optional packages that can be added to the gridpack:
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DECAY is a optional directory that contains a program that decays
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final state particles, keeping track of spin correlations at much as
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possible. It is of particular use for decays of top quarks.
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REPLACE is also an optional directory for lepton replacement. This is
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usefull for instance in the case where the generation time of the
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diagrams is critical (like for example in the case of (z/gamma>e, mu,
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tau)+4 jets including b's).
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See below for more details
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Basic Use of Gridpacks:
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Before you use the gridpack locally or over the grid, you need to
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compile the package on a machine compatible with your cluster:
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and after that it is ready to go. There is also an option to compile
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madevent with dynamic libraries. Use
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to compile with dynamic libraries for the madgraph source files. This
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will replace all makefiles with makefile_dynamic and compile using
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these new makefiles. Using dynamic libraries is greatly encouraged,
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because it can make the compiled gridpack significantly smaller.
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After a succesful compilation you can run the
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script to remove all source files and reduce the size of the
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package. Now you can just repackage and send it to some cpu in india
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or run locallly (after chmod +x run.sh)
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The DECAY directory contains a program to decay final state
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particles. It has been designed to keep track of spin correlations as
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much as possible and is particularly useful for the decay of (anti)
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top quarks E.g. for the decay of top quarks up to 95% of the
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correlations are preserved.
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Note that DECAY also needs the HELAS directory to compile.
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The DECAY package can be found in the MadGraph 5 developer's kit that
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can be downloaded from the MadGraph /MadEvent Downloads webpage or
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from Launchpad. To add the package to the gridpack, simply untar the
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gridpack to get the ./madevent/ directory and the ./run.sh
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script. Move the DECAY and the HELAS directories from the MG 5 developer's kit to the
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directory in which you untarred the gridpack, to get here the three
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directories and the one script file:
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./madevent/ ./DECAY/ ./HELAS ./run.sh
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The DECAY package is compiled automatically when
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is executed from the ./madevent directory. As input to specify the
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decays, files with the names
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should be put in the ./DECAY directory. (Where x is a number between 1
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and 20.) These files are read automatically, and one file should be
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put for each decaying particle. (E.g. for ttbar events 2 files are
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necessary: one for the decay of the top and one for the anti-top.) The
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first three lines of these files should be
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while the fourth line specifies the particle that needs decay, e.g. put
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for the decay of a top quark. The fifth line is an integer that
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specifies the decay mode. This depends on the particle that is going
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to be decayed. For top quarks it is:
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5 = ' t -> b vl l+ (e+mu)'
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6 = ' t -> b vl l+ (e+mu+ta)'
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7 = ' t -> b j j (ud+cs)'
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8 = ' t -> b anything (e+mu+ta+ud+cs)'
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and similar for the anti-top.
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Hence this file decays all top quarks (ignoring anti-tops!) in the
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event file leptonically.
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REPLACE is a package that lets the user replace particles in event
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files. This is particulary useful to save precious time in the
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generation of the diagrams. For example, the generation of Z+4jets, in
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which the Z is decay leptonically, will take (at least) three times
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longer when the three generations of leptons are specified in the
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process. Because we know that, if we assume that all of them are
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massless, the decay of Z bosons is unfavored to any specific lepton
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flavor, we could as well have generated events with only muons and
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then randomly replacing the muons in the event file by electrons or
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tau's with 33% probability for each. This is exactly what the REPLACE
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script has been designed to do. Note that for MadGraph 5, this is less
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of a problem, and in general the full process should be run
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(preferentially using sm-no_masses to get as few run directories as
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To add this functionality to the gridpack you'll have to create a
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directory 'REPLACE" after you have untarred a gridpack to get the
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./madevent/ ./REPLACE/ ./run.sh
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The replace.pl script from the ./madevent/bin/ directory as well as
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the replace_card1.dat from the ./madevent/Cards needs to be copied to
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the REPLACE directory by typing:
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cp ./madevent/bin/replace.pl ./madevent/Cards/replace_card1.dat ./REPLACE/
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(Note the in the latest version of replace, the '1' add the end of the
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filename is necessary, and can be any number between 1 and 20, to have
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the possibility of more than one replace.) In the replace_card1.dat
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the particles that needs to be replaced and the particles in which it
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needs to be replaced have to be specified by their corresponding PDG
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codes. E.g. adding the lines:
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will replace all electrons from the event file by electrons (i.e. do
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nothing), muons or taus with equal probabilities, and simultaneously
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positrons with positrons, anti-muons and anti-taus. The replace card
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that can be used in the example above in which only diagrams where the
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Z decays in muons were generated and need to be replaced by electrons
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and taus can be found here: replace_card1.dat