Beauty decay electrons in p-pb collisions using displaced electrons in ALICE

Transcription

1 Beauty decay electrons in p-pb collisions using displaced electrons in ALICE Soyeon Cho Inha University (Advised by Jin-Hee Yoon & MinJung Kweon) Heavy Ion Meeting in Andong 1

2 Motivation Study cold nuclear effect Study p+a as a benchmark for A+A Benchmark hard processes to disentangle initial from final state effects Characterize nuclear PDF at small x The gluon density rise rapidly The high energy limit of the gluon is the high gluon density limit The density must saturated for the fixed energy of gluons at high energy Heavy Ion Meeting in Andong 2

3 ALICE detector Heavy Ion Meeting in Andong 3

4 Analysis method Minimum impact parameter cut Subtract remaining background electrons The impact parameter is the core for this analysis cτ B~500 μm m B ~ 5 GeV/c 2 It is important to ensure the quality of the impact parameter, especially the run by run stability for p-pb Heavy Ion Meeting in Andong 4

5 Data set for p-pb Experiment LHC13b pass3 (10 runs) LHC13c pass2 (14 runs) Total 105 million Minimum bias event Monte Carlo LHC13b2_efix_p1 (minimum bias, 24 runs) LHC13b2_efix_p2 (minimum bias, 23 runs) LHC13d3 (HFE signal enhanced sample, 22 runs) Heavy Ion Meeting in Andong 5

6 Track selection criteria Observable Cut value η < 0.6 TPC and ITS refit Required χ 2 TPC cluster < 4 Kink daughter Rejected Number of ITS clusters 4 Requirement of SPD pixels Both Number of TPC clusters 110 Number of TPC de dx clusters (PID clusters) 80 DCA to the primary vertex in radial direction < 1 cm DCA to the primary vertex in z-direction < 2 cm Heavy Ion Meeting in Andong 6

7 Particle identification for p-pb TOF(Time of flight) Select tracks with the electron hypothesis within 3σ e ± π ± K ± p ± Reject K ± for p < 1.5 GeV/c Reject p ± for p < 3 GeV/c p Pb TPC(Time projection chamber) Select tracks in the upper half of the electron Bethe- Bloch band 0~3σ e ± p Pb Reject π ± for p < 6 GeV/c π ± Heavy Ion Meeting in Andong 7

8 Background Charm decay electrons Measured D- meson p T spectra for p-pb in ALICE Estimate decayed electron p T spectra Work in progress Heavy Ion Meeting in Andong 8

9 Background light meson decay electrons Measured π ± p T spectra for p-pb in ALICE Estimate light meson decay electron backgrounds Heavy Ion Meeting in Andong 9

10 The impact parameter is the core for this analysis It requires impact parameter QA Heavy Ion Meeting in Andong 10

11 Impact parameter distribution TOF nσ electron < 3 - MC data (24 runs) π ±, e ± p T > 0.5GeV/c All runs show the same behavior Heavy Ion Meeting in Andong 11

12 Impact parameter distribution - Experimental data [LHC13b] (10 runs) π ±, e ± All runs show the same behavior Heavy Ion Meeting in Andong 12

13 Impact parameter characteristics - Mean vs. Run number π ±, e ± The means of each run is stable within the few μm Heavy Ion Meeting in Andong 13

14 Impact parameter characteristics - Mean vs. Run number e ± The means of each run is stable within the statistical uncertainties Heavy Ion Meeting in Andong 14

15 Impact parameter characteristics - RMS vs. Run number π ±, e ± The RMS values of each run is stable Heavy Ion Meeting in Andong 15

16 Impact parameter characteristics - RMS vs. Run number e ± The RMS values of each run is stable Heavy Ion Meeting in Andong 16

17 Future plan - Obtained by inclusive analysis Large uncertainties at low p T To take meaningful result, it is required to use the method described in this talk R p Pb will be available soon, stay tune Obtained by ALICE D-meson measurement Heavy Ion Meeting in Andong 17

18 Summary For the impact parameter QA The means and RMS values of each run for both MC and experimental data are stable within the statistical uncertainties The beauty decay electron analysis for p-pb is in progress It is aimed to get R p Pb until Quark Matter Heavy Ion Meeting in Andong 18

19 Back up Heavy Ion Meeting in Andong 19

20 Impact parameter distribution - MC data [p1] (24 runs) TOF nσ electron < 3 π ±, e ± p T > 0.5GeV/c All runs show the same behavior Heavy Ion Meeting in Andong 20

21 Impact parameter distribution - MC data [p1] (24 runs) TOF nσ electron < 3 & 0.5 < TPC nσ electron < 3 e ± p T > 0.5GeV/c All runs show the same behavior Heavy Ion Meeting in Andong 21

22 Impact parameter significance distribution - MC data [p1] (24 runs) π ±, e ± p T > 0.5GeV/c All runs show the same behavior Heavy Ion Meeting in Andong 22

23 Impact parameter significance distribution - MC data [p1] (24 runs) e ± p T > 0.5GeV/c All runs show the same behavior Heavy Ion Meeting in Andong 23

24 Impact parameter distribution - MC data [p2] (23 runs) π ±, e ± p T > 0.5GeV/c All runs show the same behavior Heavy Ion Meeting in Andong 24

25 Impact parameter distribution - MC data [p2] (23 runs) e ± p T > 0.5GeV/c All runs show the same behavior Heavy Ion Meeting in Andong 25

26 Impact parameter significance distribution - MC data [p2] (23 runs) π ±, e ± p T > 0.5GeV/c All runs show the same behavior Heavy Ion Meeting in Andong 26

27 Impact parameter significance distribution - MC data [p2] (23 runs) e ± p T > 0.5GeV/c All runs show the same behavior Heavy Ion Meeting in Andong 27

28 Impact parameter distribution - MC data [LHC13d3] (22 runs) π ±, e ± p T > 0.5GeV/c All runs show the same behavior Heavy Ion Meeting in Andong 28

29 Impact parameter distribution - MC data [LHC13d3] (22 runs) e ± p T > 0.5GeV/c All runs show the same behavior Heavy Ion Meeting in Andong 29

30 Impact parameter significance distribution - MC data [LHC13d3] (22 runs) π ±, e ± p T > 0.5GeV/c All runs show the same behavior Heavy Ion Meeting in Andong 30

31 Impact parameter significance distribution - MC data [LHC13d3] (22 runs) e ± p T > 0.5GeV/c All runs show the same behavior Heavy Ion Meeting in Andong 31

32 Impact parameter distribution - Experimental data [LHC13b] (10 runs) π ±, e ± All runs show the same behavior Heavy Ion Meeting in Andong 32

33 Impact parameter distribution - Experimental data [LHC13b] (10 runs) e ± All runs show the same behavior Heavy Ion Meeting in Andong 33

34 Impact parameter significance distribution - Experimental data [LHC13b] (10 runs) π ±, e ± All runs show the same behavior Heavy Ion Meeting in Andong 34

35 Impact parameter significance distribution - Experimental data [LHC13b] (10 runs) e ± All runs show the same behavior Heavy Ion Meeting in Andong 35

36 Impact parameter distribution - Experimental data [LHC13c] (14 runs) π ±, e ± All runs show the same behavior Heavy Ion Meeting in Andong 36

37 Impact parameter distribution - Experimental data [LHC13c] (14 runs) e ± All runs show the same behavior Heavy Ion Meeting in Andong 37

38 Impact parameter significance distribution - Experimental data [LHC13c] (14 runs) π ±, e ± All runs show the same behavior Heavy Ion Meeting in Andong 38

39 Impact parameter significance distribution - Experimental data [LHC13c] (14 runs) e ± All runs show the same behavior Heavy Ion Meeting in Andong 39

40 Impact parameter significance characteristics - Mean vs. Run number π ±, e ± The means of each run is stable within the few μm Heavy Ion Meeting in Andong 40

41 Impact parameter significance characteristics - Mean vs. Run number e ± The means of each run is stable within the statistical uncertainties Heavy Ion Meeting in Andong 41

42 Impact parameter significance characteristics - RMS vs. Run number π ±, e ± The RMS values of each run is stable Heavy Ion Meeting in Andong 42

43 Impact parameter significance characteristics - RMS vs. Run number e ± The RMS values of each run is stable Heavy Ion Meeting in Andong 43

44 The total number of tracks for electrons MC data p1 [ p T Cut p T > 0.5Gev/c] Heavy Ion Meeting in Andong 44

45 The fraction of the outlier for electrons MC data p1 [ Outlier Impact parameter > 800μm] Heavy Ion Meeting in Andong 45