The low-energy electronic recoil spectrum in XENON1T provides an intriguing hint for potential new physics. At the same time, observations of horizontal branch stars favor the existence of a small amount of extra cooling compared to the one expected from the Standard Model particle content. In this note, we argue that a hidden photon with a mass of $\sim 2.8$ keV and a kinetic mixing of $\sim 10^{-15}$ allows for a good fit to both of these excesses. In this scenario, the signal detected in XENON1T is due to the absorption of hidden photon dark matter particles, whereas the anomalous cooling of horizontal branch stars arises from resonant production of hidden photons in the stellar interior.

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XENON1T和恒星冷却下的隐藏光子暗物质

XENON1T 中的低能电子反冲光谱为潜在的新物理学提供了一个有趣的提示。与此同时，与标准模型粒子含量所预期的相比，对水平分支恒星的观察有利于存在少量额外冷却。在本说明中，我们认为质量为 $\sim 2.8$ keV 且动力学混合为 $\sim 10^{-15}$ 的隐藏光子可以很好地适应这两种过量。在这种情况下，在 XENON1T 中检测到的信号是由于隐藏光子暗物质粒子的吸收，而水平分支恒星的异常冷却是由于恒星内部隐藏光子的共振产生引起的。