[[TOC]]

= Delphes Tutorial - MC4BSM July 2016 =

== Pre-requisites ==

To successfully build Delphes the following prerequisite packages should be installed:

- gcc/tcl:

For linux users gcc/tcl should be already installed. For Mac users you should install XCode.

- ROOT:

can be downloaded from https://root.cern.ch/downloading-root
Go on latest release, and download a version under "Binary distributions".

Once it is installed, type:

{{{
source [path_to_installation]/root/bin/thisroot.sh
}}}

Then simply type in a terminal:

{{{
echo $ROOTSYS
}}}

If a path is shown then root is properly installed.

=== Part I - Getting Started ===

0) Create a tutorial directory:

{{{
mkdir DelphesTutorial
cd DelphesTutorial
}}}

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) Download Z' to WW events in stdhep format
{{{
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