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在B^{0}→ψ(→l^{+}l^{-}) K_{S}^{0}(→π^{+}π^{-}) 衰变中测量CP违规
R Aaij1, A S W Abdelmotteleb2, C Abellan Beteta3
1Nikhef National Institute for Subatomic Physics, Amsterdam, Netherlands.
Physical review letters
|January 26, 2024
概括
这项研究使用LHCb数据精确地测量了B介质子衰变中的时间依赖的CP违规. 结果提供了迄今为止最准确的CKM角β测定.
科学领域:
- 高能物理 高能物理
- 粒子物理学 粒子物理学
- 量子色态动力学 量子色态动力学
背景情况:
- CP对称性破坏是粒子物理学中的一个关键现象.
- 了解B介质子衰变中的CP违规提供了对标准模型和潜在的新物理学的见解.
- 以前的测量已经限制了CKM角β,但需要更高的精度.
研究的目的:
- 测量B0和anti-B0中位子衰变中的时间依赖的CP违规参数,以达到特定的最终状态.
- 为了提供最精确的单次测量CKM角β.
- 为了提高精度,将结果与之前的LHCb测量结果结合起来.
主要方法:
- 对B0和抗B0的分析分解为J/psi(mu+mu-) KS0,psi(2S) ((mu+mu-) KS0和J/psi(e+e-) KS0,KS0变成pi+pi-.
- 使用LHCb探测器在13 TeV质量中心能量时收集的6 fb^-1的大数据集.
- 对CP违规参数S_psiKS0和C_psiKS0.0的测量
主要成果:
- 测量CP违规参数S_psiKS0的值为0.717 ± 0.013 (统计) ± 0.008 (系统).
- 测量CP违规参数C_psiKS0的值为0.008 ± 0.012 (统计) ± 0.003 (系统).
- 这次对S_psiKS0的测量是CKM角β的最精确的单一测量,超过了当前的世界平均值.
结论:
- 精确测量S_psiKS0显著改善了CKM角度β的确定.
- 这些结果有助于对粒子物理学的标准模型进行严格的测试.
- 与LHCb运行1数据的进一步结合将为β提供更精确的值.
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