Nikhef National Institute for Subatomic Physics, Amsterdam, The Netherlands.
Phys Rev Lett. 2013 Sep 13;111(11):112003. doi: 10.1103/PhysRevLett.111.112003. Epub 2013 Sep 10.
A broad peaking structure is observed in the dimuon spectrum of B+ → K+ μ+ μ- decays in the kinematic region where the kaon has a low recoil against the dimuon system. The structure is consistent with interference between the B+ → K+ μ+ μ- decay and a resonance and has a statistical significance exceeding six standard deviations. The mean and width of the resonance are measured to be 4191(-8)(+9) MeV/c2 and 65(-16)(+22) MeV/c2, respectively, where the uncertainties include statistical and systematic contributions. These measurements are compatible with the properties of the ψ(4160) meson. First observations of both the decay B+ → ψ(4160)K+ and the subsequent decay ψ(4160) → μ+ μ- are reported. The resonant decay and the interference contribution make up 20% of the yield for dimuon masses above 3770 MeV/c2. This contribution is larger than theoretical estimates.
在 B+ → K+ μ+ μ- 衰变的双μ子谱中，在动力学区域中观察到宽峰结构，其中 kaon 对双μ子系统的反冲很小。该结构与 B+ → K+ μ+ μ- 衰变和共振之间的干涉一致，具有超过六个标准偏差的统计显着性。共振的平均值和宽度分别测量为 4191(-8)(+9) MeV/c2 和 65(-16)(+22) MeV/c2，其中不确定性包括统计和系统贡献。这些测量与 ψ(4160)介子的特性相兼容。首次观察到 B+ → ψ(4160)K+ 的衰变和随后的 ψ(4160) → μ+ μ- 衰变。共振衰变和干涉贡献构成了双μ子质量超过 3770 MeV/c2 时的产量的 20%。这一贡献大于理论估计。
