标题： 在CERN SPS的缺失能量事件中搜索亚GeV暗光子的不可见衰变 显示英文标题

标题： Search for invisible decays of sub-GeV dark photons in missing-energy events at the CERN SPS

摘要： 我们报告在NA64实验中对亚GeV暗光子(A')的直接搜索，这些暗光子可能通过与光子的动能混合，在100 GeV电子撞击活性靶核的反应e^- Z\to e^- Z A'中产生。 A'会不可见地衰变为暗物质粒子，导致具有大缺失能量的事件。 在2.75\cdot 10^{9}电子/靶中未发现此类衰变的证据。 我们设定了新的\gamma -A'混合强度限制，并排除了质量小于100 MeV的不可见A'作为解释μ子g_\mu -2异常的可能。 显示英文摘要

摘要： We report on a direct search for sub-GeV dark photons (A') which might be produced in the reaction e^- Z \to e^- Z A' via kinetic mixing with photons by 100 GeV electrons incident on an active target in the NA64 experiment at the CERN SPS. The A's would decay invisibly into dark matter particles resulting in events with large missing energy. No evidence for such decays was found with 2.75\cdot 10^{9} electrons on target. We set new limits on the \gamma-A' mixing strength and exclude the invisible A' with a mass < 100 MeV as an explanation of the muon g_\mu-2 anomaly.