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研究生:杜伊婷
研究生(外文):Yi-Ting Duh
論文名稱:B^±→h^± h^0之二體稀有衰變與電荷宇稱破壞之量測
論文名稱(外文):Measurements of Branching Fractions and Direct $CP$ Violations in $B o hh^0$ decays.
指導教授:張寶棣
指導教授(外文):Pao-Ti Chang
口試委員:王名儒侯維恕熊怡張敏娟
口試日期:2011-06-21
學位類別:碩士
校院名稱:國立臺灣大學
系所名稱:物理研究所
學門:自然科學學門
學類:物理學類
論文種類:學術論文
論文出版年:2011
畢業學年度:99
語文別:英文
論文頁數:139
中文關鍵詞:高能物理加速器B物理電荷宇稱破缺稀有衰變衰變分枝比
外文關鍵詞:high energy physicsBelleKEKB physicsdirect CP violationB mesonrare decaybranching fractioncharge asymmetry
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本篇論文量測帶電B介子衰變至兩個強子機率與電荷宇稱破壞,包括B^+→K^+ π^0, π^+ π^0, K ¯^0 K^+,K^0 π^+和它們的反粒子。以Belle偵測器在正負電子對撞機內收集的772百萬對B介子做為數據,分析在Υ(4S)共振態的稀有衰變。這個分析是上一次Belle實驗數據量的1.4到1.7倍,實驗的結果也是Belle偵測器以全部的數據做最後一次的更新。

衰變分枝比的實驗結果為:
B^+→K^+ π^0=(12.62±0.31(統計)±0.56(系統))×10^(-6)
B^+→π^+ π^0=(5.86±0.26±0.38)×10^(-6)
B^+→K ¯^0 K^+=(1.11±0.19±0.05)×10^(-6)
B^+→K^0 π^+=(23.97±0.53±0.69)×10^(-6)

我們也量測了R_c=1.05±0.03±0.05和R_n=1.04±0.05±0.06,與標準模型在誤差內一致。

電荷宇稱破壞的實驗結果為:
B^+→K^+ π^0=+0.043±0.024±0.002
B^+→π^+ π^0=+0.025±0.043±0.007
B^+→K ¯^0 K^+=+0.017±0.168±0.002
B^+→K^0 π^+=-0.014±0.021±0.006
我們確認了電荷宇稱破壞在B^+→K^+ π^0為正值,且在其它衰變中,並無關測到電荷宇稱不對稱。


We report the improved measurements of branching fractions and direct $CP$ violation for charmless
$B$ decays to two hardons, $B^pm o h^pm h^0$.
$B^+ o K^+ pi^0$, $pi^+ pi^0$, $overline{K}^0 K^+$ and $K^0 pi^+$ decays and their conjugations are studied with the data of 772 million $B overline{B}$ pairs collected at $Upsilon(4S)$
resonance in Belle detector of $e^+e^-$ collider. This data sample is 1.7 times larger than the previous study for branching fraction and $CP$ violation measurements in $B^+ o overline{K}^0 K^+$ and $B^+ K^0 pi^+$ decays. Also, 1.4 times for $CP$ violation measurements in $B^+ o K^+ pi^0$ and $B^+ pi^+ pi^0$.
Besides, this study is the final update for Belle detector with all data sample.

The branching fraction are measured to be
$mathcal{BR}(B^+ o K^+ pi^0)=(12.62pm 0.31pm 0.56) imes 10^{-6}$,
$mathcal{BR}(B^+ o pi^+ pi^0)=(5.86pm 0.26pm 0.38) imes 10^{-6}$,
$mathcal{BR}(B^+ o overline{K}^0 K^+)=(1.11 ^{+0.19} _{-0.18} pm 0.05) imes 10^{-6}$ and
$mathcal{BR}(B^+ o K^0 pi^+)=(23.97 ^{+0.53} _{-0.52} pm 0.69) imes 10^{-6}$.
The first error is statistical and the second one is systematic.
We also report the rations of partial widths for $B o K pi$ and $pi pi$ decays.
$R_c = 1.05pm 0.03pm 0.05$ and $R_n = 1.04pm 0.05pm 0.06$ are consistent with Standard Model expectations.


The direct $CP$ violation measurements are reported to be
$mathcal{A}_{cp}(B^+ o K^+ pi^0)=+0.043pm 0.024(stat.)pm 0.002(syst.)$,
$mathcal{A}_{cp}(B^+ o pm^+ pi^0)=+0.025pm 0.043pm 0.007$,
$mathcal{A}_{cp}(B^+ o overline{K}^0 K^0)=+0.017pm 0.168pm 0.002$ and
$mathcal{A}_{cp}(B^+ o K^+ pi^0)=-0.014pm 0.021pm 0.006$.
We confirm the positive sign of $mathcal{A}_{cp}$ in $B^+ o K^+ pi^0$ and
no charge asymmetry be observed in other decays.


1 Introduction 1
1.1 Standard Model . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 The Cabibbo-Kobatashi-Maskawa matrix . . . . . . . . . . . . 1
1.3 CP violation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.3.1 General Formula . . . . . . . . . . . . . . . . . . . . . 4
1.3.2 CP Violation Cases in B Decays . . . . . . . . . . . . . 5
1.4 The Charmless Two-body B decays . . . . . . . . . . . . . . . 8
1.5 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2 Belle Detector 15
2.1 The KEKB Accelerator . . . . . . . . . . . . . . . . . . . . . . 16
2.1.1 Beam Pipe . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.2 Silicon Vertex Detector (SVD) . . . . . . . . . . . . . . . . . . 22
2.3 Extreme Forward Calorimeter (EFC) . . . . . . . . . . . . . . 22
2.3.1 Central Drift Chamber (CDC) . . . . . . . . . . . . . . 25
2.3.2 Aerogel Cherenkov counter system (ACC) . . . . . . . 26
2.4 Time of Flight (TOF) . . . . . . . . . . . . . . . . . . . . . . 28
2.4.1 Electromagnetic Calorimeter (ECL) . . . . . . . . . . . 31
2.5 KL and Muon Detector (KLM) . . . . . . . . . . . . . . . . . 32
3 Selection Criteria and Reconstruction 35
3.1 Data Sample . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
3.2 Event Selection . . . . . . . . . . . . . . . . . . . . . . . . . . 36
3.2.1 Charged Particle Selection . . . . . . . . . . . . . . . . 36
3.2.2 Particle Identification . . . . . . . . . . . . . . . . . . . 36
3.2.3 Neutral Pion Selection . . . . . . . . . . . . . . . . . . 37
3.2.4 Neutral Kaon Selection . . . . . . . . . . . . . . . . . . 39
3.3 Kinematic B Reconstruction . . . . . . . . . . . . . . . . . . . 41
3.4 Best Candidate . . . . . . . . . . . . . . . . . . . . . . . . . . 42
4 Background 45
4.1 Combinatorial Background . . . . . . . . . . . . . . . . . . . . 45
4.1.1 Kakuno Super Fox-Wolfram momentum(KSFW) . . . . 46
4.1.2 B flight direction (cosθB) . . . . . . . . . . . . . . . . 48
4.1.3 ΔZ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
4.2 Likelihood Ratio and the Transformation . . . . . . . . . . . . 49
4.3 BB Background . . . . . . . . . . . . . . . . . . . . . . . . . . 50
4.4 Feed-Across Background . . . . . . . . . . . . . . . . . . . . . 51
5 Fitting Strategy demonstrated by Control Sample 63
5.1 Sample . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
5.2 Consistency Check . . . . . . . . . . . . . . . . . . . . . . . . 64
5.2.1 Event Selection . . . . . . . . . . . . . . . . . . . . . . 64
5.2.2 LR Distribution of Continuum . . . . . . . . . . . . . 66
5.2.3 Correlation Check and PDF Modelling in Control Sample 68
5.2.4 Branching Fraction of B+ → D0(K+π−π0)π+ . . . . . 71
5.3 Toy Monte Carlo with 2D and 3D Fitting Strategy . . . . . . 75
5.4 Mean shift and Fudge Factor . . . . . . . . . . . . . . . . . . . 77
6 Signal Extraction 81
6.1 Correlation Check . . . . . . . . . . . . . . . . . . . . . . . . . 81
6.2 PDF Modelling . . . . . . . . . . . . . . . . . . . . . . . . . . 82
6.3 Fitting Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . 91
6.4 Fitting Results . . . . . . . . . . . . . . . . . . . . . . . . . . 94
7 Measurements for
Branching Fraction and Charge Asymmetry 97
7.1 Branching Fraction . . . . . . . . . . . . . . . . . . . . . . . . 97
7.2 Charge Asymmetry . . . . . . . . . . . . . . . . . . . . . . . . 98
7.3 Systematic Uncertainty of BR. . . . . . . . . . . . . . . . . . 103
7.3.1 LR Cut . . . . . . . . . . . . . . . . . . . . . . . . . . 105
7.3.2 Feed-Across . . . . . . . . . . . . . . . . . . . . . . . . 106
7.4 Systematic Uncertainty of Acp . . . . . . . . . . . . . . . . . . 107
8 Summary and Conclusion 109
8.1 Results and Comparison . . . . . . . . . . . . . . . . . . . . . 109
8.2 K/π Asymmetry Puzzle . . . . . . . . . . . . . . . . . . . . . 114
8.3 Partial Width . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
A Discussion on Correlation and PDF in B± → h±π0 119
A.1 Correlation and Definition of Mbc . . . . . . . . . . . . . . . . 119
A.1.1 Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
A.1.2 Background . . . . . . . . . . . . . . . . . . . . . . . . 123
A.1.3 Comparison . . . . . . . . . . . . . . . . . . . . . . . . 124
A.2 Probability Density Function . . . . . . . . . . . . . . . . . . . 127
B Ensemble Test 129


[1] http://www.fnal.gov/pub/inquiring/matter/madeof/index.html
[2] http://pdg.lbl.gov/2011/reviews/rpp2011-rev-ckm-matrix.pdf
[3] H.-Y. Cheng, C.-K. Chua and A. Soni, Phys. Rev. D 71, 014030(2005).
[4] H.-N. Li, S. Mishima and A.I. Sanda, Phys. Rev. D 72, 114005(2005).
[5] S.-W. Lin et al. (Belle Collaboration), Nature 452, 332(2008).
[6] http://ckmfitter.in2p3.fr
[7] C.-W. Chiang, M. Gronau, J.L. Rosner and D.A. Suprun, Phys. Rev. D
70, 034020 (2004)
[8] Y.-Y. Charng and H.-n. Li, Phys. Rev. D 71, 014036 (2005)
[9] W.-S. Hou, M. Nagashima and A. Soddu, Phys. Rev. Lett. 95, 141601
(2005)
[10] S. Baek, P. Hamel, D. London, A. Datta, D. A. Suprun, Phys. Rev. D
71, 057502 (2005)
[11] S.-W. Lin et al. (Belle Collaboration), Phys. Rev. Lett. 98, 181804(2007)
[12] S.-W. Lin et al. (Belle Collaboration), Phys. Rev. Lett. 99, 121601(2007)
[13] http://belle.kek.jp
[14] http://belle2.kek.jp
[15] A.Abashian et al., Nuclear Instruments and Methods in Physics Research
A 490, 117(2002)
[16] The EvtGen package home page
http://www.slac.stanford.edu/ lange/EvtGen
[17] D. J. Lange, Nucl. Instrum. Methods Phys. Res., Sect. A 462, 152
(2001).
[18] E. Barberio and Z. W﹐as, Comput. Phys. Commun. 79, 291(1994); P.
Golonka and Z. W﹐as, arXiv:hep-ph/0506026.
[19] R. Brun et al., GEANT 3.21, CERN Report DD/EE/84-1,1984.
[20] F.Fang, Belle Note 323(2000)
[21] R.A. Fisher, Annals of Eugenics 7, 179 (1936).
[22] Geoffray C. Fox and Stephen Wolfram, “”Observables for the Analysis
of Event Shapes in e+e− Annihilation and Other Processes” Phys. Rev.
Lett 41, 1581(1978)
[23] The super-Fox-Wolfram was first proposed as an extension of R2 in a
series of lectures on continuum suppression at KEK by R. Enomoto in
1999.
[24] K. Sakai et al. (Belle Collaboration), Phys. Rev. D 82, 091104(2010).
[25] Marko Staric, Belle Note 1145(2010).
[26] S.-W. Lin, Belle Note 586(2002).
[27] E. White, Belle Note 1207(2011).
[28] HFAG home page, http://www.slac.stanford.edu/xorg/hfag/
[29] W.-S. Hou,M. Nagashima and A. Soddu, Phys. Rev. Lett. 95,
141601(2005).
[30] S. Baek, P. Hamel, D. London, A. Datta, and D.A. Suprun, Phys. Rev.
D 71, 057502(2005).
[31] S. Baek, D. London, Phys. Lett. B 653, 249(2007).
[32] T.-Y Wu, Belle Note 1178(2011).
[33] M. Beneke, G. Buchalla, M. Neubert and C.T. Sachrajda, Nucl. Phys.
B 606, 245(2001)
[34] MEAN LIFE RATIO τB+/τB0 , http://pdglive.lbl.gov
[35] A.J. Buras, R. Fleischer, S. Recksiegel and F. Schwab, Eur. Phys. J.C
45, 701(2006)

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