"Table 3" of "Measurement of matter-antimatter differences in beauty baryon decays"

CERN-LHC. Differences in the behaviour of matter and antimatter have been observed in $K$ and $B$ meson decays, but not yet in any baryon decay. Such differences are associated with the non-invariance of fundamental interactions under the combined charge-conjugation and parity transformations, known as $CP$ violation. Using data from the LHCb experiment at the Large Hadron Collider, a search is made for $CP$-violating asymmetries in the decay angle distributions of $\Lambda^0_b$ baryons decaying to $p\pi^-\pi^+\pi^-$ and $p\pi^-K^+K^-$ final states. These four-body hadronic decays are a promising place to search for sources of $CP$ violation both within and beyond the Standard Model of particle physics. We find evidence for $CP$ violation in $\Lambda^0_b\to p\pi^-\pi^+\pi^-$ decays with a statistical significance corresponding to 3.3 standard deviations including systematic uncertainties. This represents the first evidence for $CP$ violation in the baryon sector.

欧洲核子研究中心大型强子对撞机（CERN-LHC）。在K介子与B介子的衰变过程中，已观测到物质与反物质行为的差异，但目前尚未在任何重子衰变中发现此类差异。这类差异与基本相互作用在电荷共轭-宇称联合变换下的非不变性相关，该现象被称为CP破坏（CP violation）。本研究借助大型强子对撞机底夸克实验（LHCb）采集的数据，针对衰变至末态pπ⁻π⁺π⁻与pπ⁻K⁺K⁻的Λ⁰_b重子，搜索其衰变角分布中的CP破坏不对称性。这类四体强子衰变是在粒子物理标准模型（Standard Model）及其之外探寻CP破坏来源的极具潜力的研究场景。我们在Λ⁰_b→pπ⁻π⁺π⁻衰变中观测到CP破坏的证据，其统计显著性（包含系统不确定度）对应3.3倍标准偏差。这是首次在重子领域观测到CP破坏的证据。