Gifu University, Gifu 501-1193.
Research Center for Nuclear Physics, Osaka University, Osaka 567-0047.
Phys Rev Lett. 2019 Feb 22;122(7):072501. doi: 10.1103/PhysRevLett.122.072501.
We report the first observation of the double strange baryon Ξ(1620)^{0} in its decay to Ξ^{-}π^{+} via Ξ_{c}^{+}→Ξ^{-}π^{+}π^{+} decays based on a 980 fb^{-1} data sample collected with the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider. The mass and width are measured to be 1610.4±6.0(stat){-4.2}^{+6.1} (syst) MeV/c^{2} and 59.9±4.8(stat){-7.1}^{+2.8}(syst) MeV, respectively. We obtain 4.0σ evidence of the Ξ(1690)^{0} with the same data sample. These results shed light on the structure of hyperon resonances with strangeness S=-2.
我们报道了首例通过 Ξ_{c}^{+}→Ξ^{-}π^{+}π^{+}衰变观察到的双奇异重子 Ξ(1620)^{0}衰变为 Ξ^{-}π^{+}的现象，这是基于 Belle 探测器在 KEKB 非对称能电子-正电子对撞机上采集的 980 fb^{-1}数据样本。该双奇异重子的质量和宽度分别测量为 1610.4±6.0(stat){-4.2}^{+6.1} (syst) MeV/c^{2}和 59.9±4.8(stat){-7.1}^{+2.8}(syst) MeV。我们用相同的数据样本获得了 Ξ(1690)^{0}的 4.0σ 证据。这些结果为具有奇异数 S=-2 的超子共振结构提供了启示。
