分类: 物理学 >> 核物理学 提交时间: 2016-09-12
摘要: We measure the decay B0s→K0K¯¯¯¯¯0 using data collected at the Υ(5S) resonance with the Belle detector at the KEKB e+e− collider. The data sample used corresponds to an integrated luminosity of 121.4 fb−1. We measure a branching fraction B(B0s→K0K¯¯¯¯¯0)=[19.6+5.8−5.1(stat.)±1.0(sys.)±2.0(NB0sB¯¯¯¯0s)]×10−6 with a significance of 5.1 standard deviations. This measurement constitutes the first observation of this decay.
分类: 物理学 >> 核物理学 提交时间: 2016-09-09
摘要: We report a search for the charmless hadronic decay B0→ηπ0 with a data sample corresponding to an integrated luminosity of 694 fb−1 containing 753×106 BB¯ pairs. The data were collected by the Belle experiment running on the Υ(4S) resonance at the KEKB e+e− collider. We measure a branching fraction B(B0→ηπ0)=(4.1+1.7+0.5−1.5−0.7)×10−7, where the first uncertainty is statistical and the second is systematic. Our measurement gives an upper limit of B(B0→ηπ0)<6.5×10−7 at 90\% confidence level. The signal has a significance of 3.0 standard deviations and constitutes the first evidence for this decay mode.