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分支分数的测量 B(B^{0}→pp[超过 ̄]pp[超过 ̄]) 和 B(B_{s}^{0}→pp[超过 ̄]pp[超过 ̄])
R Aaij1, A S W Abdelmotteleb2, C Abellan Beteta3
1Nikhef National Institute for Subatomic Physics, Amsterdam, Netherlands.
Physical review letters
|September 18, 2023
概括
这项研究报告了第一次观察罕见的B0和Bs0中子分解成四个质子. 这些发现提升了我们对粒子物理学和罕见的B介子衰变的理解.
科学领域:
- 高能物理 高能物理
- 粒子物理学 粒子物理学
- 子光谱学 子光谱学
背景情况:
- 罕见的B质子的哈德龙衰变为粒子物理学的标准模型提供了一个独特的窗口.
- 之前对B^{0}→pp[over ̄]pp[over ̄]和B_{s}^{0}→pp[over ̄]pp[over ̄]的搜索没有产生显著的结果.
- 了解这些衰变可以帮助探讨超越标准模型的新物理学.
研究的目的:
- 为了寻找和描述罕见的哈德龙衰变B^{0}→pp[over ̄]pp[over ̄]和B_{s}^{0}→pp[over ̄]pp[over ̄].
- 测量这些衰变的分支分数.
- 为理论比较和寻找新物理提供精确的测量.
主要方法:
- 分析了由LHCb实验收集的质子-质子碰撞数据.
- 使用9 fb^{-1} 的集成亮度.
- 采用数据驱动的方法来提取信号和背景估计,并进行正常化以控制衰变.
主要成果:
- 对B^{0}→pp[对 ̄]pp[对 ̄]的观察,其显著性为9.3σ.
- 观察B_{s}^{0}→pp[超过 ̄]pp[超过 ̄]的值为4.0σ.
- 测量的分支分数:B(B^{0}→pp[超过 ̄]pp[超过 ̄])=(2.2±0.4±0.1±0.1) ×10^{-8}和B(B_{s}^{0}→pp[超过 ̄]pp[超过 ̄])=(2.3±1.0±0.2±0.1) ×10^{-8}.
结论:
- 已经建立了罕见的hadronic衰变B^{0}→pp[over ̄]pp[over ̄]和B_{s}^{0}→pp[over ̄]pp[over ̄]的第一个证据.
- 测量的分支分数为罕见B衰变的理论模型提供了关键数据.
- 这些结果有助于LHC正在进行的基本物理学探索.
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