臺灣博碩士論文加值系統

我們使用B介子工廠在Upsilon介子的4s態共振質量下所累積的10.5/fb資料，
研究了兩個稀有衰變(B^0 -> Rho Pi及B^0 -> Rho K)的衰變分支比。
其中B^0 -> Rho Pi的衰變分支比為20.2+8.3-6.6x10^-6。
而由於B^0 -> Rho K的資料仍不足，結果尚不明顯，我們基於90%的信心水準，
提供了的衰變分支比上限為23.6x10^-6。

With integrated luminosity 10.5 fb^-1 data acquired at Belle,
we have studied two charmless hadronic B decay modes,
B^0 -> rho pi and B^0 -> rho K.
In this study, we have measured the branching fraction of
B^0 -> rho pi to be 20.2+8.3-6.6 x 10^-6 and
because the significance of the B^0 -> rho K channel is still
small, we only give the upper limit of this mode to be
< 23.6 x 10^-6 at 90% confidence level.

{0.1}Abstract}{2}
{1}Introduction}{1}
{1.1}Motivation}{1}
{1.2}The CP violation}{2}
{1.3}The CKM matrix}{2}
{1.4}The Measurements of the Unitary Triangle}{3}
{2}KEK B-Factory}{5}
{2.1}KEKB}{5}
{2.2}Belle Detector}{7}
{2.2.1}Beam Pipe}{7}
{2.2.2}EFC}{9}
{2.2.3}SVD}{9}
{2.2.4}CDC}{10}
{2.2.5}ACC}{10}
{2.2.6}TOF}{10}
{2.2.7}ECL}{10}
{2.2.8}KLM}{11}
{3}Data Sample and Event Selection}{21}
{3.1}Data sample}{21}
{3.2}Event selection}{22}
{3.2.1}Particle selection}{23}
{3.2.2}Gamma selection}{23}
{3.2.3}$ i ^0$ reconstruction}{23}
{3.2.4}$K/ i $ separation}{23}
{3.2.5}$\rho $ reconstruction}{25}
{3.3}B candidates selection}{25}
{3.3.1}Beam constrained mass}{25}
{3.3.2}Energy difference($\Delta E$)}{27}
{3.4}B\=B Background}{28}
{3.5}Continuum Background}{28}
{4}Event Shape Variables}{31}
{4.1}Event shape variables}{31}
{4.1.1}Thrust Angle $\mathop {\mathgroup \symoperators cos}\nolimits \theta _T$}{31}
{4.1.2}Spherocity $S_ erp $}{33}
{4.1.3}Fox-Wolfram momenta}{34}
{4.1.4}B Meson Flight Direction $\mathop {\mathgroup \symoperators cos}\nolimits \theta ^{*}_{B}$}{34}
{4.1.5}Helicity angle $\mathop {\mathgroup \symoperators cos}\nolimits \theta _H$}{34}
{4.2}Modified Fox-Wolfram Variable}{36}
{5}Methodology and Fitting Results}{39}
{5.1}Analysis Approaches}{39}
{5.1.1}Slice Cut Method}{39}
{5.1.2}Fisher's discriminant}{40}
{5.2}Likelihood Ratio Cut}{43}
{5.3}Fit results}{45}
{5.3.1}$M_b$ and $\Delta E$ shapes}{45}
{5.3.2}Signal Yields}{48}
{6}BR Measurements and Conclusion}{57}
{6.1}Reconstruction Efficiency}{57}
{6.1.1}Tracking Efficiency}{57}
{6.1.2}$ i ^0$ Efficiency}{60}
{6.2}Systematics Error Study}{60}
{6.2.1}Systematics on Particle Identification}{60}
{6.2.2}Fitting Systematics}{61}
{6.3}Breaching Ratio Measurements}{62}
{6.4}Conclusions and Prospections}{63}
{A}appendix}{73}

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