European Organization for Nuclear Research (CERN), Geneva, Switzerland.
Instituto Galego de Física de Altas Enerxías (IGFAE), Universidade de Santiago de Compostela, Santiago de Compostela, Spain.
Phys Rev Lett. 2018 Jun 1;120(22):221803. doi: 10.1103/PhysRevLett.120.221803.
A search for the rare decay Σ^{+}→pμ^{+}μ^{-} is performed using pp collision data recorded by the LHCb experiment at center-of-mass energies sqrt[s]=7 and 8 TeV, corresponding to an integrated luminosity of 3 fb^{-1}. An excess of events is observed with respect to the background expectation, with a signal significance of 4.1 standard deviations. No significant structure is observed in the dimuon invariant mass distribution, in contrast with a previous result from the HyperCP experiment. The measured Σ^{+}→pμ^{+}μ^{-} branching fraction is (2.2_{-1.3}^{+1.8})×10^{-8}, where statistical and systematic uncertainties are included, which is consistent with the standard model prediction.
使用 LHCb 实验在质心能量 sqrt[s]=7 和 8 TeV 下记录的 pp 碰撞数据，对Σ^{+}→pμ^{+}μ^{-}的稀有衰变进行了搜索，对应的积分亮度为 3 fb^{-1}。相对于背景预期，观察到事件的过剩，信号显著性为 4.1 个标准偏差。与 HyperCP 实验的先前结果相反，在双μ子不变质量分布中没有观察到显著结构。测量的Σ^{+}→pμ^{+}μ^{-}分支比为(2.2_{-1.3}^{+1.8})×10^{-8}，其中包括统计和系统不确定性，与标准模型预测一致。
