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			| One question about tracking efficiency [message #10560] | Wed, 21 April 2010 17:51  |  
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					|  Yutie Liang Messages: 12
 Registered: April 2010
 Location: Germany
 | occasional visitor | From: *physik.uni-giessen.de 
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	| Dear all, 
 I met one problem when I use the PandaRoot to do one simple study. The decay chain of my study is: Psi(3770) -> D+ D-  ->(k- pi+ pi+)( k+ pi- pi-)
 I simulated 10k signals, but only 300~400 events survived.
 I think this efficiency is too low.
 
 The following is the detailed infomation of one event from generator.  TrackIDs of (k-, pi+, pi+, k+, pi-, pi-) are always (0,1,2,3,4,5).  So, I use this trackID as PID in this study.
 
 -----------------------------------------------------
 0       9
 N      Id Ist   M1   M2   DF   DL      px      py      pz       E       t       x       y       z
 0   40443   2   -1   -1    1    2 0.00000000 -0.00000000 6.57879835 7.58363969 0.00000000 0.00000000 0.00000000 0.00000
 000
 1     411   2    0    0    3    5 -0.02342460 -0.12417095 3.72753839 4.17190509 0.00000000 0.00000000 -0.00000000 0.000
 00000
 2    -411   2    0    0    6    8 0.02342460 0.12417095 2.85125996 3.41173460 0.00000000 0.00000000 -0.00000000 0.00000
 000
 3    -321   1    1    1   -1   -1 -0.41376210 0.45311777 0.95670547 1.23916104 6.38056669 -0.03582590 -0.18990870 5.700
 94639
 4     211   1    1    1   -1   -1 0.25929310 -0.57261601 2.59179905 2.67058498 6.38056669 -0.03582590 -0.18990870 5.700
 94639
 5     211   1    1    1   -1   -1 0.13104440 -0.00467271 0.17903387 0.26215907 6.38056669 -0.03582590 -0.18990870 5.700
 94639
 6     321   1    2    2   -1   -1 0.01936009 -0.00991458 0.09054525 0.50238581 1.18131702 0.00811080 0.04299434 0.98725
 203
 7    -211   1    2    2   -1   -1 0.24342156 0.42046406 1.79061469 1.86059797 1.18131702 0.00811080 0.04299434 0.987252
 03
 8    -211   1    2    2   -1   -1 -0.23935704 -0.28637852 0.97010002 1.04875082 1.18131702 0.00811080 0.04299434 0.9872
 5203
 ---------------------------------------------------------------
 
 I checked, and found that the tracking efficiency of (k-, pi+, pi+, k+, pi-, pi-) is only about 50~60%, when MC trackID' match is required. this low efficiency of each track could explain the low efficiency of this channel.
 but, when I did single track study, the tracking efficiency of pi+ with MCtrackID match is close to 80%.  This is also low, but still acceptable considering McID match.
 
 It seems that when there are multiple tracks, 6 in my case, the tracking efficiency will become worse. Is this the problem?
 I hope that's only one bug of my analysis.
 
 
 Thanks
 
 
 yutie
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