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b至s夸克變換電荷宇稱不對稱性與極化測量

时间:2011年03月10日来源:职称论文网 作者:admin 点击:
  【关键词】稱性,與極,化測,量,不對,宇稱,s,夸克,變換,電荷,b,

校院名稱 臺灣大學
系所名稱(中) 物理研究所
系所名稱(英) Graduate Institute of Physics
學年度 93
學期 2
出版年 94
研究生(中文) 陳凱風
研究生(英文) Kai-Feng Chen
學號 D91222024
學位類別 博士
語文別 英文
口試日期 2005-05-30
論文頁數 208頁
口試委員 指導教授-熊怡
委員-侯維恕
委員-王名儒
委員-張寶棣
委員-張元翰
委員-李湘南
委員-王正祥

中文關鍵字 電荷宇稱破缺 極化 b至s夸克變換
英文關鍵字 CP violation polarization b->s transition
學科別分類 學科別>自然科學>物理

中文摘要 利用運行於Upsilon(4S)共振態之KEKB非對稱正負電子對撞機來製造、並藉由Belle偵測器所收集之兩億七千五百萬B介子對,我們量測了B0->phi K0、K+K-Ks、eta'Ks、omega Ks 等衰變之電荷宇稱(CP)破壞參數。其中一個中性B介子事例被完全重建,隨伴而來的另一B介子被用來鑑定其電荷屬性。CP破壞參數則是依靠雙B介子的原時差分佈測量而得。使用底夸克(b)至奇異(s)夸克轉換相關衰變通道,我們獲得之合併測量值偏離標準模型預測值達2.4個標準差。

我們亦利用B->phi K*衰變,提供衰變振幅以及三重乘積的測量。從末態粒子角度分佈可以測得三種不同極化螺旋態下的衰變振幅。而縱向極化振幅於中性衰變phi K*0被量測為0.45 +- 0.05 +- 0.02, 於非中性衰變phi K*+被量測為0.52 +- 0.08 +- 0.03。我們並未發現相關的CP不對稱性以及時間反轉奇態不對稱性。
英文摘要 We present measurements of CP-violating parameters in B0 -> phi K0, K+K-Ks, eta'Ks, and omegaKs decays based on a sample of 275 x 10^6 BBbar pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB energy-asymmetric e+e- collider. One neutral B meson is fully reconstructed in one of the specified decay channels, and the flavor of the accompanying B meson is identified from its decay products. CP-violation parameters for each of the decay modes are obtained from the asymmetries in the distributions of the proper-time intervals between the two B decays. The combined result for decays sensitive to the b->s transition differs from the Standard Model expectation by 2.4 standard deviations.

We also provide measurements of decay amplitudes and triple-product correlations in B -> phi K* decays. The decay amplitudes for the three different helicity states are determined from the angular distributions of final state particles. The longitudinal polarization amplitudes are found to be 0.45 +- 0.05 +- 0.02 for B0 -> phi K*0 and 0.52 +- 0.08 +- 0.03 for B+ -> phi K*+ decays. CP- and T-odd CP-violating triple-product asymmetries are measured and found to be consistent with zero.
論文目次 Abstract (i)

Table of Contents (iii)

Chapter I Prologue (1)

Chapter II CP Asymmetries in b->s Transitions (5)
II.1 The General Formalism of CP Violation (5)
II.2 The Kobayashi-Maskawa Mechanism (9)
II.3 The Unitarity Triangle (10)
II.4 CP Violation in B decays (12)
II.4.1 B0-B0bar Mixing (12)
II.4.2 Decays to CP Eigenstates (13)
II.4.3 CP Violation in B->J/psi Ks Decays (14)
II.4.4 Asymmetries in b->s Transitions (16)
II.5 Measurement of Time-dependent CP Asymmetries at Belle (18)

Chapter III Polarization in B->phi K* Decays (23)
III.1 Angular Dependence (23)
III.2 Extraction of Decay Amplitudes (27)
III.3 Triple-Product Correlations (28)
III.4 Advanced Observables and Bounds on the New Physics (31)

Chapter IV Basic Analysis Tools (33)
IV.1 Particle Identification (33)
IV.1.1 Kaon Identification (33)
IV.1.2 Electron Identification (35)
IV.1.3 Muon Identification (36)
IV.2 Flavor Tagging (37)
IV.2.1 Flavor Tagging Algoritm (38)
IV.2.2 Track-level Flavor Tagging (40)
IV.2.3 Event-level Flavor Tagging and Its Performance (41)
IV.3 Kinematic Fit (41)

Chapter V Event Reconstruction and Selection (45)
V.1 Reconstruction of B->phi Ks (45)
V.2 Reconstruction of B->K+K- Ks (48)
V.3 Reconstruction of B->eta' Ks (49)
V.4 Reconstruction of B->omega Ks (51)
V.5 Reconstruction of B0->phi K*0 and B+->phiK*+ (53)
V.6 Continuum Suppression (54)
V.7 Best Candidate and Signal Efficiencies (58)

Chapter VI Yield Extraction (63)
VI.1 Probability Density Functions (64)
VI.1.1 Signal and Continuum Events (64)
VI.1.2 Other B Decays (66)
VI.2 Determination of Signal Yields (70)
VI.3 Background Study (72)
VI.3.1 Non-OE Background (75)
VI.3.2 Non-K* Background (79)

Chapter VII Determination of CP Asymmetries (83)
VII.1 Reconstruction of the Proper Time Difference (83)
VII.2 Resolution Function (84)
VII.3 The Unbinned Maximum Likelihood Fit (89)
VII.4 Background Probability Density Functions (90)
VII.5 Results of the Fits (91)
VII.6 Systematic Uncertainties (93)
VII.7 Validation Checks (95)

Chapter VIII Extraction of Decay Amplitudes (107)


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