B介子衰變至η K π之Dalitz分析

Abstract

我們使用了日本筑波KEK之B工廠於1998至2010年間收集之771.581百萬BBbar介子對實驗數據。我們量測了B0衰變至η K+ π-三體末態的CP對稱破壞以及各中間態之衰變分支比，藉由Dalitz分析，能夠更清楚完整地了解此衰變的結構。此量測不考慮魅夸克中間態，只聚焦於底夸克至奇夸克的轉換，亦即稀有衰變的部分。至於η的衰變末態，我們只考慮了η → γγ 和 η → π+π-π0。 考慮所有中間態，在η → γγ此分支中，我們量測到的CP對稱破壞為-0.049^{+0.053}_{-0.052}+-0.046，在η → π+π-π0分支則為0.220^{+0.088}_{-0.084}+-0.040$，第一個誤差為統計誤差，第二個則是系統誤差。各中間態的衰變分支比量測結果可在此論文中見到。

We are going to determine the CP asymmetries and to measure branching fractions by Dalitz analysis for the three-body charmless hadronic B decay: B0 → η K+ π-; the branches η → γγ and η → π+π-π0 are considered. This work is based on a data sample of 771.581 million BBbar pairs collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric energy electron-positron collider. The measured branching fraction for all intermediate states are reported, we also measured Acp of inclusive charmless decay B0 → η(γγ) K+ π- = -0.049^{+0.053}_{-0.052}+-0.046 and that of B0 → η(π+π-π0) K+ π- = $0.220^{+0.088}_{-0.084}+-0.040$, the first error is statistical error and the second one is systematic error.