CMS Data Analysis School: $HH \rightarrow bb\tau\tau$ Exercise



This is a generic analysis to search for a double Higgs production in the final state with two quarks b and two leptons tau.

In this Twiki, the following colour scheme will be used:

  • Commands that you should run will be shown in a gray box, e.g.
    ls -ltr
  • Code snippets to be looked at (e.g, as examples) or edited will be shown in a pink box, e.g.
     std::cout << "This is a test" << std::endl; 
  • Output such as screen printouts will be shown in a green box, e.g.
    This is a test

Analysis Strategy

Getting set up

Login and set up environment

ssh -Y or


For this exercise, the bash shell should be used. If you are not sure what shell you are using, run:

Pippo installation $0

As editor it can be used vim or nano.

Production and Baseline Selection

The first step of this analysis is production of ntuples from miniAOD.

cmsRun .......

The code is structured in a modular way to select candidates and the objects which are useful for the final selection. BaseTupleProducer. (metti link corretti) is the class for producing BigTrees for mu-tau channel.

Tuple Skimming and Analyzer step


The following commands in an example of how to run flat tree production code (UPDATE):

./ FlatTreeProducer_mutau Analysis/dataset-das/ggH_hh_bbtautau_300.txt data/ggH_300_flat.root Analysis/config/signal-das.cfg /data/shared/Long_Exercise_X_hh_bbtautau/ @0
./ FlatTreeProducer_mutau Analysis/dataset-das/TTJets_FullLeptMGDecays.txt data/ttbar_flat.root Analysis/config/background-das.cfg /data/shared/Long_Exercise_X_hh_bbtautau/ @0
./ FlatTreeProducer_mutau Analysis/dataset-das/TauPlusX_Run2012A_22Jan2013_v1.txt data/TauPlusX_flat.root Analysis/config/data.cfg /data/shared/Long_Exercise_X_hh_bbtautau/ @0 is the script to run all of the analysis interactively. It passes command line arguments to the main class constructor. The following arguments should be provided for FlatTreeProducer_mutau constructor:

  • inputFile - input root file or list of root files that contain “big trees”
  • outputFile - file where output “flat tree” and other analysis distributions should be stored
  • configFile - configuration that should be used to run the baseline selection
  • pathPrefix - prefix to the path where big trees are stored, should be “none” if prefix is not needed
  • nEvents - maximum number of original events to process. 0, if all input events should be processed. To identify that this is a number and not a string, prefix “@” is used.

The root file produced as output contains different information:

  • two folders with plots before and after each requirement for each candidate selection
  • plots with selection sequence for each candidate
  • flat Tree part, which contains meaningful variables selected from each module and necessary for final selection

If you want to run them in parallel you can use screen. For help execute

man screen

to know which are the commands to be used. Then execute in your working folder (up to CMSSW_5_3_20/src/HHbbTauTau/)

source ~/
./ FlatTreeProducer_mutau Analysis/dataset-das/ggH_hh_bbtautau_300.txt data/ggH_300_flat.root Analysis/config/signal-das.cfg /data/shared/Long_Exercise_X_hh_bbtautau/ @0

To detach the screen do ctrl-a-d and to recover it do screen -r.

Exercise 1 - Implement AgainstElectron...

Exercise 1a - Draw Simple Distributions

Final steps of the analysis


Flat tree analysis

Exercise 5 - Determine Event Categories

Installation from official repository

Additional resources

-- MariaTeresaGrippo - 2018-12-05

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Topic revision: r2 - 2018-12-06 - KonstantinAndrosov
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