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http://madgraph.phys.ucl.ac.be/
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http://amcatnlo.cern.ch/
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Information on the process to be generated is found in the file
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index.html in this directory, which should be viewed using your web
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The executables you need to run are contained in the bin/ directory
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The bin/aMCatNLO executable open an interactive shell, from which you
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can exec different commands (some of which are also covered by the
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During the shower phase some parameters are not arbitrary as they have
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to be identical to those we have assumed in the Monte Carlo subtraction
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In particular, the following settings MUST NOT BE CHANGED:
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HERWIG6: SOFTME = .FALSE., HARDME = .FALSE., PTMIN = 0.5D0
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HERWIGPP: ReconstructionOption=General, InitialInitialBoostOption=LongTransBoost
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PYTHIA6Q: MSTJ(43) = 3, MSTJ(47) = 0, MSTJ(48) = 0, MSTJ(50) = 2,
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MSTP(67) = 2, MSTP(68) = 0, PARP(67) = 1D0, PARP(71) = 1D0.
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PYTHIA6PT: MSTP(67) = 2, MSTP(68) = 0, PARP(67) = 1D0.
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Run event generation at NLO, using the MC@NLO prescription for the
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generation of unweighted events that can be passed to a parton-shower.
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Event genration is done in three steps: in the first step, the grid
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for the integration is set. In the second step, while computing the
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cross-section, the envelope for the unweighting is computed. Finally,
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in the third step, events are generated. If no extra options are
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given, the (parton-level) .lhe file is passed to the parton-shower
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MonteCarlo, generating a file either in StdHEP (for Herwig6 and
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Pythia6) or in HEPMC format (for Herwig++). The parton shower
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MonteCarlo and the desired number of events have to be specified in
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the run_card.dat (You will be prompted to edit it just after typing
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the command). Note that, because of the way MC@NLO generates events,
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any event sample can be showered only with the parton shower it has
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been generated for. Otherwise you will obtain unphisical/wrong
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results. For the same reason, also plots obtained using the
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parton-level events in the .lhe file (without showering them) are
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If you want to first generate a smaller sample of events, and then a
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larger one with the same cuts/parameters, you can skip the
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grid-setting/ integration phases in the second run (which may be time
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consuming). To do this, when running for the second time, just use
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the -o/--only-generation option (possibly also -n/--nocompile)
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Generate showered events in StdHEP/HEPMC format (see above), for the
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parton-level .lhe event file contained corresponding to run RUN (the
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event file is Events/RUN/events.lhe.gz). All informations
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(parton-shower to be used, number of events contained in the file,
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etc...) are directly read from the file header.
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Calculate the cross section and distributions at fixed order.