ATLASNaplesStudentTutorials

Introduction

Missing Energy exercise

ssh -XY -p5022 <your_user>@atlasui03.na.infn.it

ssh -XY <your_cern_user>@lxplus.cern.ch

and setup all you need to use ROOT

export ATLAS_LOCAL_ROOT_BASE=/cvmfs/atlas.cern.ch/repo/ATLASLocalRootBase
source ${ATLAS_LOCAL_ROOT_BASE}/user/atlasLocalSetup.sh
localSetupROOT

Input files can be found here

/data/cirotto/NtupleTutorial_monojet
/afs/cern.ch/work/g/ggustavi/public/MJ135_stuffs/MJ135_minitrees

Selection criteria

1. trigger: trigger_HLT_xe70==1
2. good events: last>=X
3. leading jet pt: jet_pt.at(0)/1000 > X We divide to have it in GeV
4. eta jet TMath::Abs(jet_eta.at(0))<X
5. tight leading jet jet_fch.at(0) / jet_fmax.at(0) > X
6. MET: met_nomuon_tst_et/1000 > X
7. lepton veto n_el==X   =n_el_baseline==X  n_mu_baseline==X n_mu==X ALL TOGETHER
8. number of jet n_jet<X
9. jet-MET mimim phi: jet_met_dphi_min > XX

Suggestion : use a MakeClass to read the TTree. You can create it with the following commands:

root -l -b
TChain c
c.Add("/afs/cern.ch/work/g/ggustavi/public/MJ135_stuffs/MJ135_minitrees/run_MJ135_data.root/tree_data")
c.MakeClass("myAnalysis")

root -l -b
.L myAnalysis.C
myAnalysis pippo
pippo.Loop()

Suggestion 2: use a TSelector to read the TTree. You can create it with the following commands:

root -l -b
TChain c
c.Add("/afs/cern.ch/work/g/ggustavi/public/MJ135_stuffs/MJ135_minitrees/run_MJ135_data.root/tree_data")
c.MakeSelector("myAnalysis")

Root Guide

Root Guide 2

Root Guide Online

 
fChain->GetEntry(entry);

root -l -b

Exercises

2. Add to (1) the background MC simulations to make a data/MC comparison
Remember to set the weight correctly. Use the variable weight but remember that it is normalized to 1 fb-, so you need to scale the distributions for the proper luminosity.

3. Do the same but in the range 150 GeV < MET < 250 GeV
What do you note? which could be the explanation?

4. Test the behavior of the MET with the pileup plotting the 2D histogram of the average interaction per bunch crossing VS MET and make the histogram profile.

5. Repeat (1) and (2) in the Control Region with one muon following the same selection of the Signal Region
Add the cut on the () transverse mass 30 GeV < mT < 100 GeV. The transverse mass definition is



In this case the muon is a signal muon and not a baseline one.
Since that we are using the MET with the muons treated as invisible particles, which informations does the MET distribution give to us?

Solutions: don't cheat!

 /afs/cern.ch/user/g/ggustavi/public/MET_tutorial

Lepton exercise

Setup

ssh -XY -p5022 <your_user>@atlasui03.na.infn.it

Now copy on your local folder the code for the analysis:

cp -r /data/cirotto/TreeReader_tutorial .

Go in the directory and do de setup

cd TreeReader_tutorial 
source setROOT.sh

TreeReader

1. Have a selection to use: this means a trigger and a selection for your region of interest
2. Set your luminosity
3. Using the doPlot() method for plotting your variable

void run()
{
  //Don't modify this line
  gROOT->ProcessLine(".L TreeReader.cxx+");

  TStopwatch p;
  p.Start();

  //Write your selection and the trigger you want to use
  TString selection = " my selection";
  TString trigger =  " my trigger";
  
  //Tag for your plot
  TString tag = " my tag";


  //UPDATE YOUR PATH!
  TreeReader plot("my path); 

  //set LUMI for MC
  plot.SetLumi(myLumi); 
 
  //Set weight for bkg
  plot.SetWeight("weight"); //deafult is "weight"

  //set weight for signal
  plot.SetSigWeight("weight"); //default is weight, set weight for signal as appropriate

  //rescale signal (ONLY signal!)
  plot.SetSigScale(1); //default is 1

  //Set Bkg error on significance calculation
  plot.SetBkgError(0.15); //default is 0.

  //Set LogScale
  plot.SetLogScale(true);


  //Draw Plot
  plot.doPlot("n_jet","n_jet","n jet", selection + trigger, tag,
         6,0,6,
         false,"n_jet",3,0,6, false);
  

  plot.DrawPlot();

  p.Stop();
  p.Print();


}

Let's focus on doPlot method. It has the following structure

void TreeReader::doPlot(TString histoTitle, TString var, TString title, TString selection, TString selTag,
                         Int_t nbins, Double_t xmin, Double_t xmax,
                         Bool_t doScan, TString cut, Int_t div, Double_t min, Double_t max, Bool_t doRev)

• The variable present in the TTree is the second one, var. Be careful to use a variable present in the tree, or you will get a crash!
• histoTitle and title are strings for histogram name and its title
• selTag just a string which will give a tag to your file
• nbins, xmin, and xmax are the number of bins, minimum and maximum in the histograms (you should be familiar since you are experts of TH1!)
• We won't use the last line for now so please set doScan = false

Some advice

1. The access to vector variables it's not like in yesterday's exercises. For example, to get leading jet pt you have to write jet_pt[0] and NOT jet_pt.at(0). This is because we're passing the string to the tree.
2. You will get a file with all the histos you defined in your run macro. (Discard about the histos without name) Suggestion: maybe i can produce my histos with TreeReader when I do this Exercise

How to run

1. Open and edit run.C
2. Update your selection and your trigger
3. Don't forget to set luminosity! We're working with 2.5 fb-1
4. Write the variable you want to plot, by using doPlot method
5. run the code root -l -b -q run.C
6. You can find your plots in a folder called data
7. You also have a file with the histogram of variables you plotted (divided for each contribution)

Variables

• n_lep and n_lep_baseline: where lep can be e or mu it's the number of lepton
• mumu_m, ee_m: dilepton invariant mass
• enu_mT, munu_mT: transverse mass on lepton-MET system
• lep_pt, lep_eta,  where lep can be =e or mu, vector variables (pt is in MeV)

Exercises

Trigger items

• Level1 items: L1_2MU4, L1_2EM15, L1_TAU8, L1_J12, L1_XE70, L1_XE55
• High Level Trigger items: HLT_2mu4, HLT_2mu14, HLT_e17_lhloose, HLT_j15, HLT_j25, HLT_xe70, HLT_xe80

Trigger efficiencies

• HLT_xe70 and X is the missing energy without muons (X=met_nomuon_tst_et) (hint: use all the event as reference): use Wmunu (/data/cirotto/ NtupleTutorial_monob/SUSY7_tutorial_bkg_Wmunu.root) and compare the results with the data
• HLT_mu26_imedium and X is the leading muon pT (X=mu_pt[0]) (hint: use a proper orthogonal trigger): use Wmunu (/data/cirotto/NtupleTutorial_monob/ SUSY7_tutorial_bkg_Wmunu.root)

Help Hide Answer

             
h_num1d->Sumw2(); //numerator
h_den1d->Sumw2();      //denominator 
h_ratio->Divide(h_num1d, h_den1d, 1, 1, "B") //B option guarantees the correct errors! 

Dilepton invariant mass reconstruction

• Zmumu
  • Trigger trigger_HLT_mu26_imedium
  • Selection: number of muons and electrons, 66 < dilepton mass < 116 (in GeV)
• Zee
  • Trigger trigger_HLT_e24_lhmedium_L1EM18VH|| trigger_HLT_e24_lhmedium_L1EM20VH|| trigger_HLT_e60_lhmedium || trigger_HLT_e120_lhloose
  • Selection: number of muons and electrons, 66 < dilepton mass < 116 (in GeV)

Lepton-neutrino transverse mass reconstruction

• Wmunu
  • Trigger trigger_HLT_xe70 and MET > 200 GeV
  • Selection: number of muons and electrons
• Wenu
  • Trigger trigger_HLT_xe70 and MET > 200 GeV
  • Selection: number of muons and electrons

Working with histograms

1. What are the main backgrounds for these selections? You can check it by using the root files produced after each run of your code. Open it and retrieve the integral of each histogram.
2. Do a ratio plot, divide your data histogram by the TOTAL MC histogram, and see how is the agreement bin per bin

Help Hide Answer

             
      
h_num1d->Sumw2(); //numerator
h_den1d->Sumw2();      //denominator 
TH1F *h_ratio = (TH1F*)h_num1d->Clone(); 
h_ratio->Divide( h_den1d) 

Bonus exercise

Suggestion 2 Hide Answer

Major updates:
-- ArturoS - 2016-04-15

Responsible: ArturoS
Subject: outreach