Violation in Mixing

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2 MARCELLA BONA
Introduction The main goal of the BABAR experiment is studying �È violation in neutral � meson decays. �È symmetry violation is an expected consequence of the Standard Model with three quark generation. The Standard Model accommodates this violation through the presence of a single complex phase in the mixing �ÃÅ matrix [2, 3]. Experimental measurements in this field are important tests of the Standard Model. �È violation has been first observed in Ã decays [1] in ��. Recently, the BABAR [4] and Belle experiment [5] have observed evidence of �È violation in neutral � meson decays, making a �� significant measurement of the parameter ×�Ò ¬, ¬ being one of the angles of the Unitary Triangle. Hadronic charmless two-body � decays are important because they provide information on the other angles of the Unitary Triangle. In the SM the time-dependent �È -violating asymmetry in the channel � � � � is related to the angle «. Moreover rates asymmetries in both neutral and charged � decays into charmless final states like Ã ¦ � § , Ã Ë � ¦ , � � ¦ (� being a � or a Ã) are evidence of direct �È violation. Also ratios of branching fractions can lead to bounds on the angle . This thesis presents measurements of branching fractions of the charmless two-body modes � ¦ � Ã Ë � ¦ and � � Ã Ë Ã Ë and of the time integrated CP violating asymmetry in the charged � decays. In addition, a study of the the time-dependent asymmetry is performed in the channel � � � ¦ � § . The first chapter describes the theoretical background of the �È violation and physical meaning of the measurements presented in the following chapters. The second chapter is a description of the BABAR detector with details on the tracking system and the particle identification. The third chapter presents an analysis on inclusive Ã Ë reconstruction which has been performed in order to provide an estimate of the Ã Ë absolute reconstruction efficiency with the BABAR detector. The fourth chapter is an overview on the common issues of the hadronic charmless two-body analyses, while the fifth presents the actual analysis of the decay � ¦ � Ã Ë � ¦ whose result has been presented in Ref. [6]. The sixth chapter describes the analysis of the decay � � Ã Ë Ã Ë [7]. The seventh chapter present a preliminary result of the time-dependent analysis in � � � � decays together with a measurement of the rate asymmetry in � � Ã ¦ � § decays: this analysis is going to be published in Ref. [8].
Page 1 and 2: ÍÒ�Ú�Ö×�Ø��
Page 3 and 4: Contents Introduction . ...........
Page 5 and 6: 4 Strategy and Tools for Charmless
Page 7: 7.2 Branching fraction � � �
Page 11 and 12: 1 �È Violation in the �� Sys
Page 13 and 14: 1.2 Neutral � Mesons 7 Note, howe
Page 15 and 16: 1.2 Neutral � Mesons 9 Applying t
Page 17 and 18: 1.2 Neutral � Mesons 11 �È �
Page 19 and 20: 1.2 Neutral � Mesons 13 ��
Page 21 and 22: 1.2 Neutral � Mesons 15 � ¡�
Page 23 and 24: 1.2 Neutral � Mesons 17 and � a
Page 25 and 26: 1.2 Neutral � Mesons 19 given tim
Page 27 and 28: 1.3 The Three Types of �È Violat
Page 33 and 34: 1.4 �È Violation in the Standard
Page 43 and 44: 1.5 Determination of « 37 1.5 Dete
Page 45 and 46: 1.5 Determination of « 39 Assuming
Page 47 and 48: 1.5 Determination of « 41 Figure 1
Page 49 and 50: 1.5 Determination of « 43 b q (a)
Page 51 and 52: 1.5 Determination of « 45 � �
Page 53 and 54: 2 The BABAR Experiment 2.1 Physics
Page 55 and 56: 2.1 Physics at � � B Factory op
Page 57 and 58: 2.2 The BABAR detector. 51 Integrat
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2.2 The BABAR detector. 53 The dete
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2.2 The BABAR detector. 55 two oute
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2.2 The BABAR detector. 57 SVT Effi
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2.2 The BABAR detector. 59 324 1015
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Efficiency 2.2 The BABAR detector.
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2.2 The BABAR detector. 63 2.2.4 Th
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entries per mrad 2.2 The BABAR dete
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2.2 The BABAR detector. 67 entries
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2.2 The BABAR detector. 69 energies
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2.2 The BABAR detector. 71 The main
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Efficiency 2.2 The BABAR detector.
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2.2 The BABAR detector. 75 Table 2-
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3 Ã Ë reconstruction and efficien
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3.3 Studies on data 79 19.5° BINS
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3.3 Studies on data 81 ¯ off-reson
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3.3 Studies on data 83 0.504 0.502
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3.3 Studies on data 85 0.03 0.025 0
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3.3 Studies on data 87 0.504 0.502
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3.3 Studies on data 89 N(π + π -
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3.3 Studies on data 91 0.508 0.506
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3.3 Studies on data 93 Figure 3-13.
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3.3 Studies on data 95 0.508 0.506
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4 Strategy and Tools for Charmless
Page 105 and 106:
4.2 Event selection 99 channel sele
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4.2 Event selection 101 ÀÐ �
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4.2 Event selection 103 Figure 4-2.
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4.3 Background fighting 105 Figure
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4.4 PID selection 107 In the case o
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4.4 PID selection 109 θ c Cut Effi
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4.5 Tracking Corrections 111 Ë�
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4.6 Analysis methods 113 Ñ�Ë si
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4.6 Analysis methods 115 Events/2.5
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4.6 Analysis methods 117 Figure 4-1
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4.6 Analysis methods 119 θ c radia
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5 Measurement of Branching Fraction
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5.2 Ã Ë reconstruction 123 1 0.8
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5.3 Analysis Strategy 125 0.35 0.3
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5.4 Background Suppression and PDF
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5.5 Maximum likelihood analysis 133
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5.6 Counting analysis 145 Table 5-1
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5.7 Determination of branching frac
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6 Measurement of Branching Fraction
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6.3 The maximum likelihood analysis
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6.4 Counting analysis 157 120 100 8
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6.5 Analysis choice 159 6.5 Analysi
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6.6 Results on the Run1 data-set 16
Page 169 and 170:
6.7 Determination of the branching
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7 Analysis of the time-dependent
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7.3 Analysis strategy 167 Parameter
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7.4 Data samples and event selectio
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7.4 Data samples and event selectio
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7.5 Background characterization 173
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7.5 Background characterization 175
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Page 185 and 186:
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7.8 Validation studies 185 Figure 7
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7.8 Validation studies 187 100 75 5
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7.8 Validation studies 189 Figure 7
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7.8 Validation studies 191 Paramete
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7.9 Results 193 Parameter Fit Resul
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7.9 Results 195 Events/2 MeV/c 2 Ev
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7.10 Systematic studies 197 Categor
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7.11 Summary 199 �Ã� Ë��
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7.11 Summary 201 �Ã� Ë��
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7.11 Summary 203 Variation �Ã�
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BIBLIOGRAFIA 205 Bibliografia Chapt
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BIBLIOGRAFIA 207 [38] J. Charles, P
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BIBLIOGRAFIA 209 Chapter 7 [67] D.
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Violation in Mixing

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