王名儒臺灣大學：物理研究所李彥頡Lee, Yen-JieYen-JieLee2007-11-262018-06-282007-11-262018-06-282004http://ntur.lib.ntu.edu.tw//handle/246246/54601　　本篇論文乃是在尋找Ｂ介子衰變至超子的稀有衰變。所使用的實驗數據是由位於日本國家高能加速器中心Ｂ介子工廠(KEKB)的Belle偵測器由不對稱能量的正負電子對撞所取得的。 　　我們首度發現Ｂ^0->ｐΛbar π^-以及Ｂ^+->ΛΛbar Ｋ^+這兩種特殊的稀有衰變。而其衰變分率各為(3.97+1.00-0.80±0.56) × 10^-6以及(2.91+0.90-0.70±0.38) × 10^-6。而相關的Ｂ0We report the first observation of the charmless hyperonic B decays, Ｂ^0-->ｐΛbar π^- and Ｂ^+ --> Λ Λbar K^+ using a data sample recorded at the Upsilon(4S) resonance with the Belle detector at KEKB. The measured branching fractions are B(B^0 --> p Λbar π^- ) = (3.97+1.00 -0.80 +- 0.56) x 10^-6 and B(B^+ --> Λ Λbar K^+) = (2.91+0.90-0.70 +- 0.38) x 10^-6. We also perform a search for the related decay modes B^0--> p Λbar K^-, B^0--> pΣ^0bar π^- , and B^+ --> Λ Λbar π^+, but do not find significant signals. We set 90% confidence-level upper limit for these modes: B(B^0--> p Λbar K^-)< 8.2x10^-7 , B(pΣ^0bar π^- ) < 3.8x10^-6 and B(B^+ --> Λ Λbar π^+) < 2.8x10^-6.Chapter 1 Introduction -----------------------1 Chapter 2 KEK B-Factory ----------------------9 Chapter 3 Analysis Method --------------------25 Chapter 4 Observation of B^0--> pΛπ- --------34 Chapter 5 Observation of B+ --> ΛΛ K+--------60 Chapter 6 Conclusions and Prospects ----------91 Appendix A Λ selection systematic error -----103 Appendix B Published papers------------------10811371453 bytesapplication/pdfen-US衰變重子B介子超子高能B工廠時間對稱性破壞稀有衰變CP破壞baryonBelleKEKLambdahyperonic decayCP violationbaryonic decayT violationhigh energy physicsB mesonB factoryhyperoncharmless decayrare decaythesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/54601/1/ntu-93-R91222009-1.pdf