Reactor antineutrinos have played a significant role in establishing the standard model of particle physics and the theory of neutrino oscillations. In this article, we review the reactor antineutrino flux and in particular the reactor antineutrino anomaly (RAA) coined over a decade ago. RAA refers to a deficit of the measured antineutrino inverse beta decay rates at very short-baseline reactor experiments compared to the theoretically improved predictions (i.e. the Huber–Mueller model). Since the resolution of several previous experimental anomalies have led to the discovery of non-zero neutrino mass and mixing, many efforts have been invested to study the origin of RAA both experimentally and theoretically. The progress includes the observation of discrepancies in antineutrino energy spectrum between data and the Huber–Mueller model, the re-evaluation of the Huber–Mueller model uncertainties, the potential isotope-dependent rate deficits, and the better agreement between data and new model predictions using the improved summation method. These developments disfavor the hypothesis of a light sterile neutrino as the explanation of RAA and supports the deficiencies of Huber–Mueller model as the origin. Looking forward, more effort from both the theoretical and experimental sides is needed to fully understand the root of RAA and to make accurate predictions of reactor antineutrino flux and energy spectrum for future discoveries.

中文翻译：

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反应堆反中微子通量和异常

反应堆反中微子在建立粒子物理标准模型和中微子振荡理论方面发挥了重要作用。在本文中，我们回顾了反应堆反中微子通量，特别是十多年前提出的反应堆反中微子异常（RAA）。RAA 是指与理论上改进的预测（即 Huber-Mueller 模型）相比，在非常短的基线反应堆实验中测得的反中微子逆 β 衰变率存在缺陷。由于之前几个实验异常现象的解决导致了非零中微子质量和混合的发现，因此人们投入了大量的精力来从实验和理论上研究 RAA 的起源。进展包括观察到数据与 Huber-Mueller 模型之间的反中微子能谱差异、重新评估 Huber-Mueller 模型的不确定性、潜在的同位素相关速率赤字以及数据与新模型预测之间更好的一致性采用改进的求和方法。这些进展不利于用轻惰性中微子的假说来解释 RAA，并支持了 Huber-Mueller 模型作为起源的缺陷。展望未来，需要从理论和实验两方面付出更多努力来充分理解RAA的根源，并为未来的发现准确预测反应堆反中微子通量和能谱。