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NPE in Run14 Au+Au 200 GeV Meeting Minutes by Zhenyu - 2015/05/01

Updated on Wed, 2015-05-06 12:28. Originally created by yezhenyu on 2015-05-05 23:55.

Attendance: Xiaozhi, Mustafa, Wei, Xin, Zhenyu

1. Run14 Data
Since Kunsu was not connected, Xin pointed to his presentation at the LBNL RNC group meeting on April 27: 
https://drupal.star.bnl.gov/STAR/system/files/kunsu_20150427.pdf
Kunsu did send updates by email after the meeting:
https://drupal.star.bnl.gov/STAR/system/files/kunsu_150501.pdf

Kunsu: In slide #3-4, you can find pairAngle cut study. Actually pairAngle cut has similar effect with dynamic pairMass cut by pT. In slide #3, there is 2d histogram for pairMass vs pairAngle3d. And pairMass distribution by pT. And slide #4, you can find pairMass distribution by pairAngle cut. When I apply tight pairAngle cut, very many combinatorial background and ~20% signal is gone. I think, we don’t need apply the cut for keeping signal.

In slide #6-7, you can find partner electron pid cut study result. When I apply 13 (5) sigma cut, combinatorial background is increase 6.8 (3.6) times. It means total output file size also increase similar amounts. In slide #7,below plots are signal yield by partner nSigE cut by different pairMass cut. and 2d histograms are partner electron nSigE distribution by pT. (left: pairMass < 0.2, right: pairMass < 0.01 ) As you can see, there are too many hadrons contaminations and almost electrons are in 3 sigma. So, we should keep the 3 sigma cut.
In slide #8, You can find estimation by extent pairMass cut. When I apply 0.4 mass cut for high pT (pT > 2 GeV/c), total file size is increase only ~0.5% because almost statistics are in low pT, so I think, we can apply pairMass < 0.4 cut for pt > 2 GeV region. 
In slide #9, you can find simple QA plots for NPE tree production. 
In slide #12, Electron PID enhanced DCA distribution. I applied nSigE > 0 cut and 1/beta cut for low pT (pT < 1) electron with global beta calculation. (from Xin’s code, slide #15). In low pT, there are asymmetric electron DCA distribution because photonic electron contribution. and I don’t know why always electrons broad peak is higher then hadron’s. 

2. Run14 Simulation
We discussed the plan regarding simulation studies. The plan is to first integrate EvtGen into STAR enviroment with the help of Jason, understand and verify the outputs from EvtGen make sense, and then do detector simulation. 

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