四、一与零：量化ANITA-IV、KM3NeT和IceCube之间的超高能中微子反常
Four, One, and None: Quantifying the Ultra-High-Energy Neutrino Anomaly Across ANITA-IV, KM3NeT, and IceCube
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中文总结 AI 辅助
研究ANITA-IV、KM3NeT和IceCube之间中微子事件率的矛盾，通过构建有效面积等进行联合分析。结果表明在标准模型下，仅方向和时间变化无法协调观测结果与零结果，无论是全天空幂律通量还是罕见瞬变源假设。
中文摘要 AI 辅助
ANITA-IV报告的四个近地平线类中微子事件以及KM3NeT观测到的超高能轨道状事件KM3-230213A意味着中微子事件率与IceCube未出现相应事件存在矛盾。本工作对这些事件进行联合分析，考虑到IceCube没有相应事件的情况。构建了三个探测器的半解析、能量和方向相关的有效面积，并考虑了随时间变化的ANITA-IV和KM3NeT曝光。对于全天空幂律通量变化的情况，三个探测器的测量事件率无法再现。最佳拟合配置预测约五个IceCube事件，但严重低估了ANITA-IV和KM3NeT的计数。若事件源于短持续时间瞬变，矛盾可大幅缓解，但需高度微调。若罕见瞬变随机分布，会有额外源影响IceCube曝光。结论是，在标准模型内，仅方向和时间变化无法使ANITA-IV和KM3NeT观测结果与IceCube的零结果相协调。
英文摘要
The four near-horizon neutrino-like events reported by ANITA-IV and the ultra-high-energy track-like event KM3-230213A observed by KM3NeT imply neutrino event rates that are in tension with the absence of corresponding events at IceCube. In this work, we perform a joint analysis of these events, taking into account the absence of any corresponding ones at IceCube. We construct semi-analytic, energy- and direction-dependent effective areas for the three detectors and account for the time-dependent ANITA-IV and KM3NeT exposures. For a diffuse all-sky power-law flux varying both the normalization and the spectral index, the measured event rates across the three detectors are not reproduced. The best-fit configuration, corresponding to a tension of $\sim7.5σ$, predicts approximately five IceCube events while strongly underpredicting the ANITA-IV and KM3NeT counts. In contrast to the diffuse scenario, the tension can be substantially alleviated if the events arise from short-duration transients that occur exactly along the observed directions during the ANITA-IV and KM3NeT detection windows. Such a realization, however, is highly fine-tuned. If rare transients are instead distributed randomly across the full sky over the $\sim15$-year IceCube observation period, additional sources inevitably contribute to the IceCube exposure. For benchmark populations with a probability of approximately $10^{-4}$ to produce four favorable transients at ANITA-IV, the best-fit configuration of sources, out of $10^5$ Monte Carlo realizations, remains in $5.9σ$ tension. We conclude that, within the Standard Model, directional and temporal variations alone can not reconcile the ANITA-IV and KM3NeT observations with the IceCube null result, under both a diffuse all-sky flux and a rare-transient source hypothesis.
