Pi0 project software for events selection.

James Werner

Tracks and Gamma lists.

Every charged particle produced in the collision interacts with Drift Chamber producing tracks that are identified and momentum, energy, charge, etc are estimated. A complete list of variables are available at http://www.slac.stanford.edu/BFROOT/www/doc/workbook/nanomicro/v8.8/. BtaCandidate contains all information and is used in the program with iterators to retrieve event components. Gamma particles are detected by EMC, and information available for each gamma is available in the same type of BtaCandidate list. These two lists (charged particles and gammas) allow to reconstruct every event detected by Babar detector.

However, users do not know what type of particle left the information in the detector. Reconstruction software suppose all particles are pions (mass 139.5 MeV).

Selectors

If the user wants only one type of particle (for example kaons or muons), there are selectors that build list for different type of particles. The list of particles and selectors are available at http://www.slac.stanford.edu/BFROOT/www/Physics/Tools/Pid/selector_changes.html and http://www.slac.stanford.edu/BFROOT/www/Physics/Tools/Pid/Selectors/r14a/selectors.html.

Selectors read the original tracks and classify them using several different algorithms, creating a new list of tracks that match the criteria. There is a relation between selector accuracy and number of events efficiency. More tight the selector, less events will be selected. By the other hand, more loose the selector more events will be selected with background increase.

To learn more about particle identification, see http://www.slac.stanford.edu/BFROOT/www/Physics/Tools/Pid/documentation.html , http://www.slac.stanford.edu/BFROOT/www/Physics/Tools/Pid/pid.html, and http://www.slac.stanford.edu/BFROOT/www/Physics/Tools/Pid/primer.html

Events selection criteria and Runs

Run 1 and 2 used the Job Submission PROTOTYPE, and Run3 use the production version of Job Submission based in the Job Submission Specification. The following criteria were used to select events:

  1. Muon list must have only one member. I used a muNNVeryLoose list for Run1 and Run2 and muNNVeryTight for Run3.
  2. Pion list must have only one member. I used a piLHVeryLoose list for Run1 and Run2 and piLHVeryTight for Run3.
  3. Pi0 reconstruction follow 2 methodologies:
    1. All gammas combine with each other (Run1).
    2. Every gamma only contributes in one combination, taked randomly from first occurrence (Run2 and Run3).
  4. The number of pi0s define the resonance. If there are 2 pi0s, the resonance is a1. This is important to group the data in the correct histograms.
  5. The resonance mass peak defines what events will be used to plot resonance energy.
The software generates Excel csv files with all information of each selected event. CSV stands for Comma Separed Values, and is a very easy way to interface with Excel Spreadsheet. The available information is: 
    
  
  1.  Track information:
  
      
    
    1. number of event: sequencial number of the event for each file submission.
    
    2. TrackQNPi0: identify tracks from PiC (Q= N for negative and P for Positive) with N pi0s (N=1,2,3,or 4).
    
    3. Sequence number, starting from zero.
    
    4.  theta in Lab reference frame.
    
    5.  phi in Lab reference frame.
    
    6.  Px, Py, Pz: momentum in MeV.
    
    7.  Total momentum module.
    
    8.  Total energy.
  
    
  Example:
	1657, TrackN2Pi0, 0, 0.895102, 2.72354, -3.49173, 1.30616, 2.95818, 4.7591, 4.76115
	1657, TrackN2Pi0, 1, 0.958139, -0.642978, 0.514588, -0.651476, 0.566021, 1.00479, 1.01444

  
  2.  Muon information:
  
      
    
    1. number of event: sequencial number of the event for each file submission.
    
    2. MuonQNPi0: identify muon with the other tau decaying in PiC with N pi0s.
    
    3. charge.
    
    4.  Px, Py, Pz: momentum in MeV.
    
    5.  Total momentum module.
    
    6.  Total energy.
  
    
  Example:
	1657, MuonN2Pi0, -1, 0.514588, -0.651476, 0.566021, 1.00479, 1.01033

  
  3.  Charged Pion:
  
      
    
    1. number of event: sequencial number of the event for each file submission.
    
    2. CPiQNPi0: identify the charged pion.
    
    3.  theta in Lab reference frame.
    
    4.  phi in Lab reference frame.
    
    5.  Px, Py, Pz: momentum in MeV.
    
    6.  Total momentum module.
    
    7.  Total energy.
    
    8.  Mass.
  
    
  Example:

	1657, CPiN2Pi0, 0.958139, -0.642978, 0.514588, -0.651476, 0.566021, 1.00479, 1.01444, 139.57018

  
  4.  Gammas:
  
      
    
    1. number of event: sequencial number of the event for each file submission.
    
    2. GamaQ: identify the gammas.
    
    3. Sequence number, starting from zero.
    
    4. In what pi0 it was used, if not equal -1.
    
    5.  theta in Lab reference frame.
    
    6.  phi in Lab reference frame.
    
    7.  Px, Py, Pz: momentum in MeV.
    
    8.  Total momentum module.
    
    9.  Total energy.
  
    
  Example:

	1657, GamaN, 0, 0, 1.13179, -0.506549, 2.22847, -1.23644, 1.19669, 2.81548, 2.81548
	1657, GamaN, 1, 1, 1.26983, 2.42817, -0.222897, 0.192918, 0.0915016, 0.308663, 0.308663
	1657, GamaN, 2, 1, 0.781218, 2.1564, -0.0871403, 0.131393, 0.158986, 0.223906, 0.223907
	1657, GamaN, 3, 0, 1.19115, -0.36771, 0.341468, -0.131544, 0.146005, 0.393982, 0.393982

  
  5. Reconstructed pi0s:
  
      
    
    1. number of event: sequencial number of the event for each file submission.
    
    2. NPi0Q: identify reconstructed pi0s from 2 gammas.
    
    3. Sequence number, starting from zero.
    
    4. what gammas wer used.
    
    5.  Px, Py, Pz: momentum in MeV.
    
    6.  Total momentum module.
    
    7.  Total energy.
    
    8.  Mass.
  
    
  Example:

	1657, 2Pi0N, 0, 0, 3, 2.56994, -1.36798, 1.3427, 3.20605, 3.20946, 0.147835
	1657, 2Pi0N, 1, 1, 2, -0.310037, 0.324311, 0.250488, 0.513853, 0.53257, 0.139949


  
  6. Reconstructed ressonance:
  
      
    
    1. number of event: sequencial number of the event for each file submission.
    
    2. WNPi0Q: Identify reconstructed ressonance from pi0s and charged pion.
    
    3.  Px, Py, Pz: momentum in MeV.
    
    4.  Total momentum module.
    
    5.  Total energy.
    
    6.  Mass.
  
    
  Example:

	1657, W2Pi0N, 2.77449, -1.69515, 2.15921, 3.90301, 4.75647, 2.71855

Merging all information

Every file from the dataset will run in a different computer in parallel, and will produce different outputs. The following script merge all files and generate csv files for each type of particle and charge. This final file will be open in Excel and plots will be generated to allow study and model the decay process. 


      1   rm global.txt
      2   cat Tau*.txt | grep "Track\|Muon\|CPi\|Pi0\|Gama\|numMuon\|numPion\|numPi0\|numGam\|numMassa" > global.txt
      3   cat global.txt | grep " CPiP1Pi0" > CPiP1Pi0.csv
      4   cat global.txt | grep " CPiN1Pi0" > CPiN1Pi0.csv
      5   cat global.txt | grep " CPiP2Pi0" > CPiP2Pi0.csv
      6   cat global.txt | grep " CPiN2Pi0" > CPiN2Pi0.csv
      7   cat global.txt | grep " CPiP3Pi0" > CPiP3Pi0.csv
      8   cat global.txt | grep " CPiN3Pi0" > CPiN3Pi0.csv
      9   cat global.txt | grep " CPiP4Pi0" > CPiP4Pi0.csv
     10   cat global.txt | grep " CPiN4Pi0" > CPiN4pi0.csv
     11   cat global.txt | grep " MuonP1Pi0" > MuonP1Pi0.csv
     12   cat global.txt | grep " MuonN1Pi0" > MuonN1Pi0.csv
     13   cat global.txt | grep " MuonP2Pi0" > MuonP2Pi0.csv
     14   cat global.txt | grep " MuonN2Pi0" > MuonN2Pi0.csv
     15   cat global.txt | grep " MuonP3Pi0" > MuonP3Pi0.csv
     16   cat global.txt | grep " MuonN3Pi0" > MuonN3Pi0.csv
     17   cat global.txt | grep " MuonP4Pi0" > MuonP4Pi0.csv
     18   cat global.txt | grep " MuonN4Pi0" > MuonN4Pi0.csv
     19   cat global.txt | grep " TrackP1Pi0" > TrackP1Pi0.csv
     20   cat global.txt | grep " TrackN1Pi0" > TrackN1Pi0.csv
     21   cat global.txt | grep " TrackP2Pi0" > TrackP2Pi0.csv
     22   cat global.txt | grep " TrackN2Pi0" > TrackN2Pi0.csv
     23   cat global.txt | grep " TrackP3Pi0" > TrackP3Pi0.csv
     24   cat global.txt | grep " TrackN3Pi0" > TrackN3Pi0.csv
     25   cat global.txt | grep " TrackP4Pi0" > TrackP4Pi0.csv
     26   cat global.txt | grep " TrackN4Pi0" > TrackN4Pi0.csv
     27   cat global.txt | grep " GamaP" > GamaP.csv
     28   cat global.txt | grep " GamaN" > GamaN.csv
     29   cat global.txt | grep " 1Pi0P" > 1Pi0P.csv
     30   cat global.txt | grep " 1Pi0N" > 1Pi0N.csv
     31   cat global.txt | grep " 2Pi0P" > 2Pi0P.csv
     32   cat global.txt | grep " 2Pi0N" > 2Pi0N.csv
     33   cat global.txt | grep " 3Pi0P" > 3Pi0P.csv
     34   cat global.txt | grep " 3Pi0N" > 3Pi0N.csv
     35   cat global.txt | grep " 4Pi0P" > 4Pi0P.csv
     36   cat global.txt | grep " 4Pi0N" > 4Pi0N.csv
     37   cat global.txt | grep " W1Pi0P" > W1Pi0P.csv
     38   cat global.txt | grep " W1Pi0N" > W1Pi0N.csv
     39   cat global.txt | grep " W2Pi0P" > W2Pi0P.csv
     40   cat global.txt | grep " W2Pi0N" > W2Pi0N.csv
     41   cat global.txt | grep " W3Pi0P" > W3Pi0P.csv
     42   cat global.txt | grep " W3Pi0N" > W3Pi0N.csv
     43   cat global.txt | grep " W4Pi0P" > W4Pi0P.csv
     44   cat global.txt | grep " W4Pi0N" > W4Pi0N.csv
     45   cat global.txt | grep numMuon > numMuon.csv
     46   cat global.txt | grep numPion > numPion.csv
     47   cat global.txt | grep numPi0 > numPi0.csv
     48   cat global.txt | grep numGam > numGam.csv
     49   cat global.txt | grep numMassa2g > nummassa2g.csv
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Copyright 2004 Manchester University
Feedback to: jamwer@hep.man.ac.uk