Charmed baryon decay asymmetry in e^＋e^- annihilation

We propose to measure the decay asymmetry parameters in the hadronic weak decays of singly charmed baryons, such as Λc^＋ →Λπ^＋, Σ^0π^＋, pK0, Ξ0c →Ξ-π＋and Ω^0c →Ω^-π^＋. The joint angular formulae for these processes are presented, and are used to extract the asymmetry parameters in e^＋e^-annihilation data. Base on the currentΛ＋c data set collected at BESIII, we estimate the experimental sensitivities to measure the parameters αΛπ＋forΛ＋c →Λπ＋, αΣ＋π0for Λc^＋ →Σ＋π^0 and αΣ0π＋for Λc^＋ →Σ^0π^＋.

CP asymmetries in Strange Baryon Decays

While indirect and direct C P violation（CPV） has been established in the decays of strange and beauty mesons, no CPV has yet been found for baryons. There are different paths to finding C P asymmetry in the decays of strange baryons; they are all highly non-trivial. The Hyper CP Collaboration has probed CPV in the decays of singleΞ and Λ [1]. We discuss future lessons from e~＋e^-collisions at BESⅢ/BEPCⅡ： probing decays of pairs of strange baryons, namely Λ, Σ and . Realistic goals are to learn about non-perturbative QCD. One can hope to find CPV in the decays of strange baryons; one can also dream of finding the impact of New Dynamics. We point out that an important new era will start with the BESIII/BEPCII data accumulated by the end of 2018. This also supports new ideas to trigger J/ψ→■Λ at the LHCb collaboration.

Λ_(c)^(+)→Λh^(+)和Λc+→∑^(0)h^(+)(h=K,π)衰变道CP破坏的寻找和其分支比与衰变不对称参数的测量

本文报告了粲重子Λ_(c)^(+)的四个弱衰变道Λ_(c)^(+)→Λh^(+)和Λ_(c)^(+)→∑^(0)h^(+)(h=K,π)的系列研究.基于在KEKB能量不对称的正负电子对撞机上的Belle探测器收集的980 fb-1数据样本,作者测量了粲重子两体单卡比玻压低(SCS)衰变过程中的直接电荷共轭-宇称(CP)不对称:ACPdir(Λ_(c)^(+)→ΛK^(+))=+0.021±0.026±0.001和ACPdir(Λ_(c)^(+)→∑^(0)K^(+))=+0.025±0.054±0.004;精确测量了衰变不对称参数(α)和其引起的CP不对称度:AC^(α)_(P)(Λ_(c)^(+)→ΛK^(+))=-0.023±0.086±0.071和AC^(α)_(P)(Λ_(c)^(+)→∑^(0)K^(+))=+0.08±0.035±0.14.这是粲重子SCS衰变的第一个AC^(α)_(P)结果;其次,作者在实验上利用粲重子衰变来寻找超子CP破坏,即利用Λ_(c)^(+)→(Λ,∑^(0))π^(+)衰变获得AC^(α)_(P)(Λ→pπ-)=+0.013±0.007±0.011.以上测量均未发现重子CP破坏的证据.此外,该文还报告了Λ_(c)^(+)两个SCS衰变道的分支比测量:B(Λ_(c)^(+)-ΛK^(+))=(6.57±0.17±0.11±0.35)×10^(-4)和B(Λ_(c)^(+)→∑^(0)K^(+))=(3.58±0.19±0.06±0.19)×10^(-4),这些均为目前最精确的结果.