Changes between Version 2 and Version 3 of WorkBook/TutorialBologna

Timestamp:

Jun 8, 2016, 1:56:43 PM (8 years ago)

Author:

Michele Selvaggi

Comment:

--

WorkBook/TutorialBologna

@@ -18 +18 @@
 Once it is installed, type:
 
-{{{source [path_to_installation]/root/bin/thisroot.sh}}}
+{{{
+source [path_to_installation]/root/bin/thisroot.sh
+}}}
 
 Then simply type in a terminal:
 
-{{{echo $ROOTSYS}}}
+{{{
+echo $ROOTSYS
+}}}
 
 If a path is shown then root is properly installed.
 
  
+== MadGraph5/MadEvent basic tutorial (@Leading Order) ==
+
+In this part you are going to learn how to generate pardon-level and showered events with MadGraph5 (interfaced with Pythia6). 
+
+0) Create a new directory:
+
+{{{
+mkdir DelphesTutorial
+cd DelphesTutorial
+}}}
+
+1) Download and install MG5 by typing in a terminal:
+{{{
+wget https://launchpad.net/mg5amcnlo/2.0/2.4.0/+download/MG5_aMC_v2.4.0.tar.gz
+tar xzvf MG5_aMC_v2.4.0.tar.gz
+}}}
+2) Launch MG5:
+{{{
+cd MG5_aMC_v2_4_0
+./bin/mg5_aMC
+}}}
+3) Install Pythia6 and !MadAnalysis:
+{{{
+install pythia-pgs
+install MadAnalysis
+}}}
+4) Generate a LO Drell-Yan process:
+{{{
+generate p p > e+ e-
+display diagrams
+}}}
+5) Generate a LO Higgs process:
+{{{
+generate p p > h > e+ e- mu+ mu-
+}}}
+The diagram generation fails ... do you understand why? Type instead:
+{{{
+import model heft
+generate p p > h > e+ e- mu+ mu-
+display diagrams
+}}}
+This generates also diagrams containing photon internal lines. To veto that diagram type the following:
+{{{
+generate p p > h > e+ e- mu+ mu-  / a
+display diagrams
+}}}
+6) Let's generate some events
+{{{
+output pp_h_eemm
+launch pp_h_eemm
+}}}
+
+You will be prompted with a screen asking questions ... Type "ENTER". Another screen comes and asks you if you want to edit a bunch of configuration cards:
+
+ - "param_card.dat" is where the parameters of the model are stored (masses, couplings)
+ - "run_card.dat" is where the parameters of run are defined (ecm, number of events,
+    generation level cuts ..)
+ - "pythia_card.dat" is where parameters of the shower are defined
+
+Open "param_card.dat" and "run_card.dat" by typing respectively "1" and "2"and have a look at them, but do not modify them for now. The editor is "vi", so to quit type ":q". Type ENTER to launch the parton-level generation.
+
+7) When it's done, you should be prompted with a web browser. If not quit MG5 by typing "exit", and open the html file that was created and the end of the run with your web browser:
+{{{
+firefox [MG5DIR]/pp_h_eemm/Events/index.html
+}}}
+Click on "Results and Event Database" and then on "LHE plots". Have a look at the automatically generated parton-level plots. Explain the Ecm plot (this is the total invariant mass of the system, i.e of the four final state leptons).
+8) Enter in MG5 again, and type:
+{{{
+./bin/mg5_aMC
+import model heft
+}}}
+{{{
+generate p p > h , h > e+ e- mu+ mu- / a
+display diagrams
+}}}
+Then:
+{{{
+output pp_h_eemm_res
+launch pp_h_eemm_res
+}}}
+Note the different syntax.
+This time, when you will be prompted with the screen asking questions ... Type "1". This will activate parton and hadronization with Pythia6, and then type ENTER.
+When the generation is done, have a look again at the parton-level plots.
+
+7) Generate a new set of events, this time setting in the param_card mH = 750 GeV. !! Note that since we are keeping the higgs width value corresponding to mH = 125 GeV, this won't be a proper SM higgs with mH = 750 GeV !!
+
+For this we don't need to re-generate the diagrams, we can simply type "launch" and edit the param_card by changing the higgs mass when prompted. If everything worked smoothly you should have two event samples with 10k events each. Events are stored in [MG5DIR]/pp_h_eemm_res/Events/run_01(02)
+
+Now to quit MG5, type "exit". In each run sub-directory, only two files are interesting for us:
+
+- "unweighted_events.lhe" contains hard-interaction events only, pre-hadronization and PS,
+it is human readable, in so-called Les-Houches Event format (in short LHE)
+- "tag_1_pythia_events.hep" contains showered and hadronized events, it is the event file
+that we are going to give as input to the Delphes simulation.
+
+This ends the very basic introduction to MG5. For an extensive list of tutorials, lectures about this tool (including matching, NLO generation, etc..) , have a look at the !MadGraph School 2015 page:
+
+http://www.physics.sjtu.edu.cn/madgraphschool/
+
+== Delphes Tutorial ==
+
+=== Part I - Getting Started ===
+
+0) Go back to the !DelphesTutorial directory
+
+1) Get Delphes:
+{{{
+git clone https://github.com/delphes/delphes.git
+cd delphes
+}}}
+or, if you don't have "git" installed, simply type:
+{{{
+wget http://cp3.irmp.ucl.ac.be/downloads/Delphes-3.3.2.tar.gz
+tar -zxf Delphes-3.3.2.tar.gz
+mv Delphes-3.3.2 delphes
+cd delphes
+}}}
+2) Install it:
+{{{
+./configure
+make -j 4
+}}}
+3) Unzip the event files previously generated with MG5, and move them in your delphes directory
+{{{
+gunzip ../MG5_aMC_v2_4_0/pp_h_eemm_res/Events/run_01/tag_1_pythia_events.hep.gz
+gunzip ../MG5_aMC_v2_4_0/pp_h_eemm_res/Events/run_02/tag_1_pythia_events.hep.gz
+}}}
+{{{
+mkdir -p input
+mv ../MG5_aMC_v2_4_0/pp_h_eemm_res/Events/run_01/tag_1_pythia_events.hep input/pp_h_eemm_m125.hep
+mv ../MG5_aMC_v2_4_0/pp_h_eemm_res/Events/run_02/tag_1_pythia_events.hep input/pp_h_eemm_m750.hep
+}}}
+
+4) Finally, let's run Delphes. If the compilation went right, you should have three executables:
+
+- DelphesLHEF  -> should not be used
+- DelphesHepMC -> to be used on HepMC input format (*.hepmc)
+- DelphesSTDHEP -> to be used on STDHEP input format (*.hep)
+
+Type for instructions (note that output file comes before input file):
+{{{
+./DelphesSTDHEP
+}}}
+To run on our your input file, type:
+{{{
+./DelphesSTDHEP cards/delphes_card_CMS.tcl delphes_output_m125.root input/pp_h_eemm_m125.hep
+}}}
+5) Open freshly produced Delphes output with ROOT, and explore it.
+{{{
+root -l delphes_output_m125.root
+TBrowser t;
+}}}
+In the browser, double click on the "delphes_output_m125.root", and then on the "Delphes" tree. Play around by double clicking on the various branches/observables.
+
+You can then play plot important observable with a simple selection with the following syntax:
+{{{
+Delphes->Draw("Muon.PT", "Muon.PT > 20");
+Delphes->Draw("Electron.PT", "Electron.PT > 20");
+}}}
+- Note 1: Delphes - tree name, it can be learnt e.g. from TBrowser
+- Note 2: Muon/Electron - branch name; PT - variable (leaf) of this branch
+{{{
+Delphes->Draw("Muon.Eta", "Muon.PT > 20");
+Delphes->Draw("Electron.Eta", "Electron.PT > 20");
+Delphes->Draw("Jet_size","Electron_size > 1 && Muon_size > 1");
+}}}
+Objects are already ordered in PT, you can then plot leading ele/mu in this way:
+{{{
+Delphes->Draw("Muon[0].PT", "Muon.PT > 20");
+Delphes->Draw("Electron[0].PT", "Electron.PT > 20");
+}}}
+For more information on ROOT trees:
+
+http://cp3.irmp.ucl.ac.be/downloads/RootTreeDescription.html
+
+=== Part II - Run a macro-based analysis on Delphes output ===
+
+1) The macro examples/Example3.C produces resolution plots comparing reconstructed vs MC truth quantities. Run it on the delphes output:
+
+root -b -q examples/Example3.C'("delphes_output_m125.root")'
+
+It produces a bunch of plots in "png" format. Open them with your favourite image viewer:
+
+{{{
+open *.png
+}}}
+or
+{{{
+eog *.png
+}}}
+
+Understand: 
+
+ - Why is the eta resolution plot for electron and muons different compared to photons?
+ - Where do photons come from?
+ - Why is the jet resolution plot shifted?
+
+
+2) Let's now run a real event selection, and plot some interesting quantities. We select events with:
+
+-   >= 2 opposite sign isolated electrons , pT > 10 GeV, |eta| < 2.5
+-   >= 2 opposite sign isolated muons , pT > 10 GeV, |eta| < 2.5
+
+Construct 3 invariant masses and fill them in histograms:
+
+- min( m(e+ e-), m(mu+ mu-) )
+- max( m(e+ e-), m(mu+ mu-) )
+- m (e+ e- mu+ mu-)
+
+Open the "HZZ.C" macro with your favorite text editor, and make sure you understand what it
+does. Then run it:
+{{{
+root -b -q  examples/HZZ.C'("delphes_output_m125.root")'; 
+}}}
+Some plots are produced. Open the produced png file. 
+
+- Explain the left plot.
+- Appreciate the effect of detector resolution by comparing the gen and reco histograms
+
+Now redo this analysis, but this time using the mH = 750 GeV input file. Do not edit directly the HZZ.C file, make a copy of it and edit the copy rather.
+
+- Spot and explain the differences with the mH = 125 GeV case.
+