--MG source


1. Running standalone Madgraph.(Interactive mode)

-Madgraph is a tool for Matrix Element(ME) level calculation. In LHE physics, we calculate physics process by energy scale - from large to small scale / from hard to soft process. As QCD is perturbative at high energy scale, we describe a physics process in order of alpha_s at ME level(hard process level). At this level, we constuct a process's skeleton.

[figure how a phyiscs generator works] feynman diagram -> soft process

Let's start with DrellYan process ( q q~ -> Z/gamma* -> l+ l-)

wget https://cms-project-generators.web.cern.ch/cms-project-generators/MG5_aMC_v2.6.5.tar.gz

tar xf MG5_aMC_v2.6.5.tar.gz

cd MG5_aMC_v2_6_5/bin/


generate p p > l+ l-

output myrun

launch myrun

You can see the xsec of the process.

Let's go to the detail information of the process.

- Diagram.

ls myrun/SubProcesses/P1_qq_ll/*.ps

- Event record

open lhe file using text editor.

vi myrun/Events/run_01/unweighted_events.lhe.gz


emacs -nw myrun/Events/run_01/unweighted_events.lhe.gz )

Find <event> block



5 1 +1.6860000e+03 8.89432000e+01 7.54677100e-03 1.30543100e-01

-1 -1 0 0 0 501 -0.0000000000e+00 +0.0000000000e+00 +2.2398225191e+01 2.2398225191e+01 0.0000000000e+00 0.0000e+00 1.0000e+00

1 -1 0 0 501 0 +0.0000000000e+00 -0.0000000000e+00 -8.8298210922e+01 8.8298210922e+01 0.0000000000e+00 0.0000e+00 -1.0000e+00

23 2 1 2 0 0 +0.0000000000e+00 +0.0000000000e+00 -6.5899985731e+01 1.1069643611e+02 8.8943200127e+01 0.0000e+00 0.0000e+00

-11 1 3 3 0 0 +1.6824537576e+01 -5.9830707237e+00 +1.7740426939e+01 2.5171113363e+01 0.0000000000e+00 0.0000e+00 1.0000e+00

11 1 3 3 0 0 -1.6824537576e+01 +5.9830707237e+00 -8.3640412670e+01 8.5525322750e+01 0.0000000000e+00 0.0000e+00 -1.0000e+00

in Les Houches Event(LHE) format.(https://arxiv.org/abs/hep-ph/0109068)


2. Gridpack

A Gridpack is a precompiled file to run event generation of a specific process. It is more proper to large production of samples because it already contains all information and all setups are done for a process. Let's make a gridpack of DY process.

git clone git@githubNOSPAMPLEASE.com:soarnsoar/genproductions.git -b DAS2019

cd genproductions/bin/MadGraph5_aMCatNLO

./gridpack_generation.sh dyellell0j_5f_LO_MLM cards/examples/dyellell0j_5f_LO_MLM

ls dyellell0j_5f_LO_MLM_slc6_amd64_gcc630_CMSSW_9_3_16_tarball.tar.xz

-- JunhoChoi - 2019-11-04

Topic attachments
I Attachment History Action Size Date Who Comment
PDFpdf LHEexplanation.pdf r1 manage 64.5 K 2019-11-04 - 10:49 JunhoChoi LHEformat
PNGpng LHEexplanation.png r1 manage 463.2 K 2019-11-04 - 10:51 JunhoChoi  
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