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Pythia Analysis ver 3.1: Analysis of set C5 events using geant record

Analysis of all setC5 events using geant tracks and vertices

 

In this analysis I looked at all QCD background events from setC5, which has an integrated luminosity on the order of what we expect to get in data. I also looked at W events from setC2 Wprod. The details of both event samples can be found here. This analysis was done using version 3.1 of my code which uses geant vertices and tracks, meaning we have perfect tracking for the cuts. All transverse energy is event ET and an energy scaling factor of 1.23 is used. All samples are scaled to LT=800 inverse pb.

 

Cuts:

I make 14 cuts which are described below. These cuts have been loosened compared to those in version 3.0, now each cut throws away no more that 1% of the signal. I have also added conditions to cuts 5 and 8 to reject events where no charged track was found. Plots of the cut spectra can be found here. Pages 1-11 show the cut spectra after the 3 preliminary phase space cuts have been made (spectra of the first 3 cuts are not shown). All events must pass the first three cuts to be analysed further. Pages 12-18 show cut spectra 8-14 after cuts 1-7 have been applied to them. Pages 19-29 show all the cut spectra after all cuts but their own have been applied.

  1. Cut 1: Require that the geant vertex be in the region [-70,-50]
  2. Cut 2: Require that the trigger patch ET>20GeV
  3. Cut 3: Require that the high tower not be in eta bin 1 or 12
  4. Cut 4: Isolation cut - Ration of the ET in the trigger patch to the ET in an iso cone with r=0.45. Require > 0.94 to pass
  5. Cut 5: Track iso cut - Number of geant charged tracks with pT>0.5GeV in an iso cone with r=0.7. Require < 5 and > 0 to pass
  6. Cut 6: Awayside isolation cut - ET in a region Pi +/- 0.7 radians from the high tower in phi. Require < 9.0 to pass
  7. Cut 7: Awayside track cut - Number of geant charged tracks with pT>0.5GeV in same region as cut 6. Require < 10.0 to pass
  8. Cut 8: Track near high tower - Number of geant charged tracks with pT>5.0GeV in an iso cone with r=0.7. Require there be 1 and only 1 track to pass
  9. Cut 9: Ratio of energy in two highest towers in trigger patch to energy in all towers in trigger patch. Require > 0.75 to pass
  10. Cut 10: Ratio of energy in 7 highest adjacent U strips under the patch to the energy in all U strips under the patch. Require > 0.45 to pass
  11. Cut 11: Ratio of energy in 7 highest adjacent V strips under the patch to the energy in all V strips under the patch. Require > 0.45 to pass
  12. Cut 12: Number of hit U strips in sector containing the trigger patch. Require < 52 to pass
  13. Cut 13: Number of hit V strips in sector containing the trigger patch. Require < 54 to pass
  14. Cut 14: Ratio of energy in patch post-shower layer to full energy in patch. Require < 0.002 to pass

 I have also made several 2-D plots of other quantities which my provide good electron/hadron discrimination. These plots can be found here.

  • Page 1 is a plot of the iso radius (r=0.7) ET Vs. the trigger patch ET
  • Page 2 is a plot of the away side ET Vs. the trigger patch ET
  • Page 3 is a plot of the trigger patch ET Vs. the number of charged tracks above 0.5GeV in the away side region
  • Page 4-6 show the same plots as pages 1-3 after cuts 1-7 have been applied
  • Page 7-9 show the same plots as pages 1-3 after all cuts have been applied
  • Page 10 is a plot of the trigger patch energy Vs. the post shower energy
  • Page 11 is a plot of the energy in both the U and V strips under the trigger patch Vs. the energy in all post shower layers under the trigger patch
  • Page 12 is a plot of the energy in both the U and V strips under the trigger patch Vs. the energy in all 2nd pre-shower layers in the trigger patch
  • Page 13 is a plot of the trigger patch energy Vs. the energy in all 2nd pre-shower layers in the trigger patch
  • Page 14-17 show the same plots as pages 10-13 after cuts 1-7 have been applied
  • Page 18-21 show the same plots as pages 10-13 after all cuts have been applied

 

Spectra

The plots showing the effect of the various cuts on the trigger patch ET spectrum can be found here. Pages 1-14 show the effect that the first 3 cuts plus the individual cut has on the trigger patch ET spectrum. So, for example, page 7 shows the spectrum after cuts 1, 2, 3, and 7. Pages 15-26 show the effects that a number of cuts applied sequentially has on the spectrum. In all plots the black curve is the detected ET spectrum before any cuts have been made and the red curve is the ET spectrum after the cuts in question have been applied.

 

Fig 1: This plot shows the effects of all the cuts applied in sequence on the trigger patch ET spectrum. For the QCD sample: The raw spectrum contains 2.6E6 events in the region 20-70, the spectrum after the phase space cuts (1-3) contains 2.2E6 events, and the spectrum after all cuts contains 1.5E4 events. For the W sample: The raw spectrum contains 4645 events in the region 20-70, the spectrum after the phase space cuts contains 3747 events and the spectrum after all cuts contains 3378 events.

 

Fig 2: This plot shows the final trigger patch ET spectra after all cuts have been applied. The QCD background is in black and the W signal is in red.