MadGraph5_aMC@NLO

MadGraph/Pythia6 interface

Asked by Lucia Perrini

Dear experts,
I am in trouble with MadGraph/Pythia6 interface.
I am trying to hadronize Z+jets events at 8TeV using the following fragment

process.generator = cms.EDFilter("Pythia6HadronizerFilter",
    ExternalDecays = cms.PSet(
        Tauola = cms.untracked.PSet(
            UseTauolaPolarization = cms.bool(True),
            InputCards = cms.PSet(
                mdtau = cms.int32(0),
                pjak2 = cms.int32(0),
                pjak1 = cms.int32(0)
            )
        ),
        parameterSets = cms.vstring('Tauola')
    ),
    UseExternalGenerators = cms.untracked.bool(True),
    pythiaPylistVerbosity = cms.untracked.int32(1),
    pythiaHepMCVerbosity = cms.untracked.bool(True),
    comEnergy = cms.double(8000.0),
    jetMatching = cms.untracked.PSet(
        MEMAIN_showerkt = cms.double(0),
        MEMAIN_maxjets = cms.int32(-1),
        MEMAIN_minjets = cms.int32(-1),
        MEMAIN_qcut = cms.double(-1),
        MEMAIN_excres = cms.string(''),
        MEMAIN_etaclmax = cms.double(-1),
        MEMAIN_nqmatch = cms.int32(5),
        outTree_flag = cms.int32(0),
        scheme = cms.string('Madgraph'),
        mode = cms.string('auto')
    ),

but I have the error

----- Begin Fatal Exception 20-Nov-2012 11:50:21 CET-----------------------
An exception of category 'Generator|PartonShowerVeto' occurred while
   [0] Processing run: 1 luminosityBlock: 1
   [1] Running path 'generation_step'
   [2] Calling beginLuminosityBlock for module Pythia6HadronizerFilter/'generator'
Exception Message:
The MGParamCMS header does not specify the jet matching parameter "etaclmax", but it is requested by the CMSSW configuration.
----- End Fatal Exception -------------------------------------------------

could you help me to fix this?
Thanks!

Cheers,
Lucia

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Johan Alwall (johan-alwall) said : 		#1

Hello Lucia,

It looks like you are working inside an experimental framework (CMS or ATLAS), not the version of the programs that are downloaded from our website. I would suggest you contact your MC/generator group with this question.

All the best,
Johan

Revision history for this message
Christopher A. George (r-george) said : 		#2

I am having the same issue, will post the solution for others reading this. It seems that the "-1" parameter requires the etaclmax to be set by your LHE file. If the LHE file does not have such a parameter, it complains. You can get rid of this by setting it locally -- it is a maximum, so you can set it to an arbitrarily high number if you don't want to cut on this variable.

Can you help with this problem?

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