A search for millicharged particles, a simple extension of the standard model, has been performed with the ArgoNeuT detector exposed to the Neutrinos at the Main Injector beam at Fermilab. The ArgoNeuT liquid argon time projection chamber detector enables a search for millicharged particles through the detection of visible electron recoils. We search for an event signature with two soft hits (MeV-scale energy depositions) aligned with the upstream target. For an exposure of the detector of 1.0×10^{20} protons on target, one candidate event has been observed, compatible with the expected background. This search is sensitive to millicharged particles with charges between 10^{-3}e and 10^{-1}e and with masses in the range from 0.1 to 3 GeV. This measurement provides leading constraints on millicharged particles in this large unexplored parameter space region.

中文翻译：

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使用费米实验室（Fermilab）的ArgoNeuT实验，改进了对带电粒子的限制。

搜索了带电粒子，这是标准模型的简单扩展，已使ArgoNeuT检测器在费米实验室的主注入器光束中暴露于中微子。ArgoNeuT液态氩气时间投射室检测器可通过检测可见电子反冲来搜索带电粒子。我们搜索与上游目标对齐的两个软命中（MeV级能量沉积）的事件签名。对于1.0×10 ^ {20}质子的检测器在目标上的曝光，已观察到一个候选事件，与预期的背景兼容。该搜索对电荷在10 ^ {-3} e和10 ^ {-1} e之间且质量范围在0.1到3 GeV之间的微电荷粒子敏感。