Recently, an anomalous excess was found in the electronic recoil data collected at the XENON1T experiment. The excess may be explained by an axionlike particle (ALP) with a mass of a few keV and a coupling to electron of $g_{ae}\sim {10}^{-13}$, if the ALP constitutes all or some fraction of local dark matter (DM). In order to satisfy the x-ray constraint, the ALP coupling to photons must be significantly suppressed compared to that to electrons. This strongly suggests that the ALP has no anomalous couplings to photons; i.e., there is no $\mathrm{U}(1{)}_{\mathrm{PQ}}\text{−}\mathrm{U}(1{)}_{\mathrm{em}}\text{−}\mathrm{U}(1{)}_{\mathrm{em}}$ anomaly. We show that such anomaly-free ALP DM predicts an x-ray line signal with a definite strength through the operator arising from threshold corrections, and compare it with the projected sensitivity of the ATHENA x-ray observatory. The abundance of ALP DM can be explained by the misalignment mechanism, or by thermal production if it constitutes a part of DM. In particular, we find that the anomalous excess reported by the XENON1T experiment as well as the stellar cooling anomalies from white dwarfs and red giants can be explained simultaneously better when the ALP constitutes about 10% of DM. As concrete models, we revisit the leptophilic anomaly-free ALP DM considered in K. Nakayama, F. Takahashi, and T. T. Yanagida [Phys. Lett. B 734, 178 (2014)] as well as an ALP model based on a two Higgs doublet model in the Supplemental Material.

中文翻译：

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XENON1T来自无异常轴突暗物质的过量现象及其对恒星冷却异常的影响

最近，在XENON1T实验中收集到的电子反冲数据中发现了异常过量。可以用质量为几keV且与电子耦合的轴状粒子（ALP）解释过量。$G_{\mathrm{一种}Ë}〜{10}^{-13}$，如果ALP构成局部暗物质（DM）的全部或部分。为了满足x射线约束，与电子相比，必须显着抑制与光子的ALP耦合。这有力地表明，ALP与光子之间没有异常耦合。即，没有$\mathrm{ü}（\mathrm{1个}{）}_{\mathrm{PQ}}\text{-}\mathrm{ü}（\mathrm{1个}{）}_{\mathrm{EM}}\text{-}\mathrm{ü}（\mathrm{1个}{）}_{\mathrm{EM}}$异常。我们证明了这种无异常的ALP DM通过阈值校正预测了通过操作员具有确定强度的X射线线信号，并将其与ATHENA X射线天文台的预计灵敏度进行了比较。ALP DM的丰度可以通过未对准机制来解释，或者可以通过热量产生来解释，如果它构成DM的一部分。特别是，我们发现，当ALP占DM的大约10％时，可以同时更好地解释XENON1T实验报告的异常过量以及白矮星和红巨星的恒星冷却异常。作为具体模型，我们将重新审视中山K.，高桥F和柳田TT所考虑的无亲脂异常ALP DM 。来吧 乙 734，第178页（2014）]，以及基于补充材料中两个希格斯双峰模型的ALP模型。