Converted photon and π0 discrimination based on H cut-based analysis Zhen Zhang IHEP 04-10-09
CSA07 samples converted photon candidate from: π0 from: 160000 events /H120_gammagamma_gluonfusion/CMSSW_1_6_7-CSA07-1193937318/RECO 160000 events π0 from: /Gamjet/CMSSW_1_6_7-CSA07-1192835335/RECO 1.1M events /Jets_Pt50up/CMSSW_1_6_7-CSA07-1198935308/RECO 1 M events
I. converted photon and π0 candidates selection Converted photon candidates are selected as H to cut-based selection (PTDR) : Photon selection: photon candidates are reconstructed using the hybrid clustering algorithm in the barrel and the island clustering algorithm in the endcaps ET1, ET2 > 30GeV (release to Et>40, 25 GeV now) |η|<2.5 Isolation No tracks with pt>1.5 GeV present within ΔR<0.3 around the direction of the photon candidate. We consider tracks with hits in at least two layers of the silicon pixel detector. Sum of Et of the ECAL basic clusters within 0.06<ΔR<0.35 around the direction of the photon candidate <6 GeV in barrel, <3 GeV in endcaps Sum of Et of the HCAL towers within ΔR<0.3 around the direction of the photon candidate<6 GeV(5 GeV) in barrel (endcaps) If one of the candidates has |eta|>1.4442 the other has to satisfy also: Sum of Et of the ECAL<3, Sum of Et of the HCAL<5 GeV
Number of tracks associated with a SuperCluster for converted photon
The reason of one track corresponding to a SuperCluser
In the TMVA analysis, I will study the SuperCluter has a track and more that one track separately
Input variables for one track case
Input variables for one track case
training and test results
BDT training and test output
Input variables for more than one track case
Input variables for more than one track case
training and test results
BDT training and test output
TMVA application I will select the converted photon candidate in gamma jet sample. The criterion is that the converted photon candidate does not corresponding a photon at generator lever, i.e., exclude the prompt photon.
The BDT output in application one track case more thanone track case 47% 48% The BDT output shape of converted photon candidate from pi0 in gamma jet sample is almost the same as the training shape. This support our result is believable. For reject rate(48%.47%) is lower than training resluts(55,50%) is caused by the variable conpho_closestSC_dR which depends on sample to some extent.
Converted photon and pi0 discrimination in CMS NOTE IN 2007/032 provided by G.Anagnostou the results from ORCA the results from CMSSW, so I don’t use it in the analysis
Some discusses on my thesis the title of my thesis： How to organize the four chapters of HZ gamma, HVV, converted photon and pi0 discrimination and cosmic ray analysis?