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观察罕见的巴里昂衰变B^{+}→pΛ[over ̄]并测量其弱衰变参数
R Aaij1, A S W Abdelmotteleb2, C Abellan Beteta3
1Nikhef National Institute for Subatomic Physics, Amsterdam, Netherlands.
Physical review letters
|February 22, 2026
概括
研究人员使用LHCb数据首次观察了B+→pΛ[over ̄]衰变. 测量了分支分数,弱衰变参数表明可比的S波和P波幅度.
科学领域:
- 粒子物理学 粒子物理学
- 高能物理 高能物理
- 子光谱学 子光谱学
背景情况:
- B+质子是一种含有底反夸克和上夸克的子.
- 了解B+中子衰变,可以了解大自然的基本力量,特别是弱相互作用.
- 之前的研究已经探索了B+中子的各种衰变模式,但B+→pΛ[over ̄]没有被观察到.
研究的目的:
- 报告B+→pΛ[over ̄]衰变的第一个观察结果.
- 为了测量这种衰变模式的分支分数.
- 为了确定弱衰变参数αB,并研究导致的衰变幅度.
主要方法:
- 分析了由LHCb实验收集的质子对质子碰撞数据,该实验的质量中心能量为13 TeV.
- 从2016-2018年的数据中利用5.4fb-1的集成亮度.
- 使用B+→K0Sπ+衰变作为准确的分支分数测量的规范化通道.
主要成果:
- 观察到B+→pΛ[over ̄]衰变的信号显著度超过7个标准偏差.
- 测量出的分支分数是 (1.24±0.17±0.05±0.03) ×10−7.7 的.
- 弱衰变参数αB被确定为0.87−0.29+0.26±0.09.
结论:
- 对B+→pΛ[over ̄]衰变的第一个证据为研究B介质子物理学提供了新的道.
- 测量的分支分数和弱衰变参数提供了关于这种衰变的基本动态的关键信息.
- 结果表明存在可比的S波和P波衰变幅度,有助于更深入地了解粒子相互作用.
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