Rare B meson decays - mathieu trocmé

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II- Physical Background 17 * + K * + K * + K * + K s s d d u u s s d d u u s s u u u u s s u u u u 0 K S + π 0 K L + π + K 0 π + K 0 π Figure 7: Feynman diagrams of all the possible <strong>decays</strong> coming from * + 0 * + − the decay of the K in the channel B → K π . The last decay is forbiddenbecause of Zweig suppression.
III- Analysis Method 18 III- ANALYSIS METHOD III.1- Data Sample and Preselection: The data sample on which this analysis is performed was collected at BABAR between 0 0 1999 and 2002 and is made up of 61.6 ± 0.68 millions of B B events. In order to reduce the 0 0 overall analysis time, the data is firstly skimmed at BABAR by discarding all the B / B 0 0 candidates that are irrelevant to the decay under study. For each B / B candidate, discriminating variables are calculated. If they satisfy a loose set of selection conditions, the 0 0 B / B candidate is integrated to a data structure called ‘Ntuple’. Over 200 variables are dumped into the Ntuple. This therefore contains all the relevant information concerning a 0 0 B / B candidate, such as its mass, energy, momentum, …, as well as those of its daughter particles, and some event shape and particle identification information. This pre-processing of data is called preselection. The Ntuple used here contains 7 893 939 III.2- The Cut and Count Method (CCM): III.2.1- Principle of the CCM: 0 0 B / B candidates. At the Ntuple level, another set of selection requirements or ‘cuts’ is applied to remove 0 0 all the irrelevant background events. If all the conditions are satisfied by a B / B candidate, this is counted. Formally, such an analysis is referred to as a ‘selection cut based counting analysis’. The discriminating variables used in this analysis can be divided in 5 categories. These are described hereafter.
Page 1 and 2: UNIVERSITY OF BRISTOL DEPARTMENT OF
Page 3 and 4: Acknowledgements 2 ACKNOWLEDGEMENTS
Page 5 and 6: Table of contents 4 III.3.5- Backgr
Page 7 and 8: I- Introduction 6 A way to quantify
Page 9 and 10: II- Physical Background 8 These thr
Page 11 and 12: II- Physical Background 10 s b gWVu
Page 13 and 14: II- Physical Background 12 II.3- B
Page 15 and 16: II- Physical Background 14 To creat
Page 17: II- Physical Background 16 As a res
Page 21 and 22: III- Analysis Method 20 Number of e
Page 23 and 24: III- Analysis Method 22 III.2.2.3-
Page 29 and 30: III- Analysis Method 28 0 B ? 0 B ?
Page 31 and 32: III- Analysis Method 30 III.3.2- MC
Page 33 and 34: III- Analysis Method 32 With, MC Ns
Page 35 and 36: III- Analysis Method 34 By integrat
Page 37 and 38: III- Analysis Method 36 III.3.4- Er
Page 39 and 40: III- Analysis Method 38 All the sel
Page 41 and 42: III- Analysis Method 40 For example
Page 43 and 44: III- Analysis Method 42 III.5- Over
Page 45 and 46: IV- Results 44 IV- RESULTS IV.1- Fi
Page 47 and 48: IV- Results 46 IV.2- MC Efficiency
Page 49 and 50: IV- Results 48 Another common notat
Page 51 and 52: V- Discussion 50 V- DISCUSSION As d
Page 53 and 54: V- Discussion 52 Concerning the opt
Page 55 and 56: Appendix 54 APPENDIX This appendix
Page 57 and 58: References 55 [1] [2] [3] [4] [5] [

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