We argue that the fixed target experiment PS191 operating on a proton beam of 19.2 GeV at CERN in the eighties was sensitive to hypothetical light scalars produced by mesons and decaying to charged particles. The experiment was dedicated to searches for sterile neutrinos produced in weak meson decays and decaying into final states with pairs of charged particles: electrons and muons. Two charged tracks from the same point have been adopted as the signal signature. Exploiting the same signature we use the negative results of searches at PS191 and place new limits on the light scalars coupled to the Standard Model (SM) particles via mixing with the Higgs boson. In particular, previously allowed region of masses 100–150 MeV and mixing above $4\times {10}^{-4}$ is disfavored. Our analysis can be extended straightforwardly to models with other patterns of scalar couplings to SM particles.

我们认为，80 年代在 CERN 的 19.2 GeV 质子束上运行的固定目标实验 PS191 对介子产生并衰减为带电粒子的假设光标量敏感。该实验致力于寻找在弱介子衰变中产生的无菌中微子，并衰变成具有带电粒子对的最终状态：电子和介子。来自同一点的两条带电轨道已被用作信号签名。利用相同的特征，我们使用 PS191 搜索的负面结果，并对通过与希格斯玻色子混合而耦合到标准模型 (SM) 粒子的光标量施加新的限制。特别是，以前允许的质量区域为 100-150 MeV 并且混合高于$4\times {10}^{-4}$不受欢迎。我们的分析可以直接扩展到具有与 SM 粒子的其他标量耦合模式的模型。