Violation in Mixing

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148 Measurement of Branching Fractions for � ¦ � Ã � ¦ decays Table 5-12. Summary of branching fraction results for the global likelihood fit. Shown are the central fit values ÆË and measured branching fractions �Ê. For the ÃÃ Ë mode we show the � confidence level upper limit signal yield and branching fraction. For Æ Ë and �Ê the first error is statistical and the second is systematic. MARCELLA BONA Mode ÆË Ã Ë � Stat. Sig. (�) �Ê � Ã � �� Ã Ã (� �) ( ) � ��
6 Measurement of Branching Fractions for � � Ã Ë Ã Ë Decays This chapter describes the charmless two-body analyses for all-neutral final state containing Ã Ë mesons. The latest results from CLEO [65] on decays with all-neutral final state is � � � Ã Ã � � ¢ � . 6.1 Data samples and event selection The analyses presented in this chapter use the data samples described in Sec. 4.1 and the selection described in Sec. 4.2. Issues related to reconstruction of Ã Ë mesons have been discussed in Sec. 5.2. For the Ã Ë we require ØÃË��Ø � �, where ØÃË is the measured (2-d) decay time and �Ø is its error. The mass window is ¬ � � Å�Î� ( ��). tightened to ¬ ¬ Å � � Å Ã Ë � mesons are constructed by combining two ÃË candidates. To choose between multiple candidates in the same events, we use the variable Æ � ¡Å ÃË value of Æ. ¡Å ÃË � and we keep the candidates with the smallest We use the kinematic variables Ñ�Ë and ¡�. We require �� Ñ�Ë � �� Î� and �¡�� Î. From the conservative ¡� resolution value of � Å�Î, the signal region is defined as �¡�� Î (i.e. 4 times the ¡� resolution). The regions � � ¡� � � ��Î and � � ¡� � � ��Î are referred to as the lower and upper side-bands, respectively, and each of them has the same width of the signal region (0.2 ��Î). We also create a control sample collecting those events rejected by the � Ó× �Ë� cut, in order to study the ARGUS function shape in different ranges of �¡�� values. 6.2 Analysis strategy Previous experiments have found no evidence of the decay � � ÃËÃË: the theoretical expectation for the � � Ã Ã branching ratio is less than � , but considering the efficiency, given that we reconstruct Ã � Ã Ë � � � , we expect to see Ã Ë Ã Ë events with an effective branching ratio less than � . Since we aim for setting the lowest upper limit possible on the branching ratio measurement, we have investigated two possible strategies to search for this channel in the BABAR data sample: the usual global likelihood technique and a counting analysis optimization. With a toy Monte Carlo in the first case and with the on-
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ÍÒ�Ú�Ö×�Ø��
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Contents Introduction . ...........
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4 Strategy and Tools for Charmless
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7.2 Branching fraction � � �
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Introduction The main goal of the B
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1 �È Violation in the �� Sys
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1.2 Neutral � Mesons 7 Note, howe
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1.2 Neutral � Mesons 9 Applying t
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1.2 Neutral � Mesons 11 �È �
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1.2 Neutral � Mesons 13 ��
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1.2 Neutral � Mesons 15 � ¡�
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1.2 Neutral � Mesons 17 and � a
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1.2 Neutral � Mesons 19 given tim
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1.3 The Three Types of �È Violat
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1.4 �È Violation in the Standard
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1.5 Determination of « 37 1.5 Dete
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1.5 Determination of « 39 Assuming
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1.5 Determination of « 41 Figure 1
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1.5 Determination of « 43 b q (a)
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1.5 Determination of « 45 � �
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2 The BABAR Experiment 2.1 Physics
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2.1 Physics at � � B Factory op
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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
Page 103 and 104: 4 Strategy and Tools for Charmless
Page 105 and 106: 4.2 Event selection 99 channel sele
Page 107 and 108: 4.2 Event selection 101 ÀÐ �
Page 109 and 110: 4.2 Event selection 103 Figure 4-2.
Page 111 and 112: 4.3 Background fighting 105 Figure
Page 113 and 114: 4.4 PID selection 107 In the case o
Page 115 and 116: 4.4 PID selection 109 θ c Cut Effi
Page 117 and 118: 4.5 Tracking Corrections 111 Ë�
Page 119 and 120: 4.6 Analysis methods 113 Ñ�Ë si
Page 121 and 122: 4.6 Analysis methods 115 Events/2.5
Page 123 and 124: 4.6 Analysis methods 117 Figure 4-1
Page 125 and 126: 4.6 Analysis methods 119 θ c radia
Page 127 and 128: 5 Measurement of Branching Fraction
Page 129 and 130: 5.2 Ã Ë reconstruction 123 1 0.8
Page 131 and 132: 5.3 Analysis Strategy 125 0.35 0.3
Page 133 and 134: 5.4 Background Suppression and PDF
Page 139 and 140: 5.5 Maximum likelihood analysis 133
Page 151 and 152: 5.6 Counting analysis 145 Table 5-1
Page 153: 5.7 Determination of branching frac
Page 157 and 158: 6.3 The maximum likelihood analysis
Page 163 and 164: 6.4 Counting analysis 157 120 100 8
Page 165 and 166: 6.5 Analysis choice 159 6.5 Analysi
Page 167 and 168: 6.6 Results on the Run1 data-set 16
Page 169 and 170: 6.7 Determination of the branching
Page 171 and 172: 7 Analysis of the time-dependent
Page 173 and 174: 7.3 Analysis strategy 167 Parameter
Page 175 and 176: 7.4 Data samples and event selectio
Page 177 and 178: 7.4 Data samples and event selectio
Page 179 and 180: 7.5 Background characterization 173
Page 181 and 182: 7.5 Background characterization 175
Page 191 and 192: 7.8 Validation studies 185 Figure 7
Page 193 and 194: 7.8 Validation studies 187 100 75 5
Page 195 and 196: 7.8 Validation studies 189 Figure 7
Page 197 and 198: 7.8 Validation studies 191 Paramete
Page 199 and 200: 7.9 Results 193 Parameter Fit Resul
Page 201 and 202: 7.9 Results 195 Events/2 MeV/c 2 Ev
Page 203 and 204: 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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