The finite size of a neutrino wave packet at creation can affect its oscillation probability. Here, we consider the electron antineutrino wave packet and decoherence in the context of the nuclear reactor-based experiment JUNO. Given JUNO’s high expected statistics [$\sim 100\mathrm{k}$ IBD events (${\overline{\nu }}_{e}p\to e^{+}n$)], long baseline ($\sim 53\mathrm{km}$), and excellent energy resolution [$\sim 0.03/\sqrt{E_{\mathrm{vis}}(\mathrm{MeV})}$], its sensitivity to the size of the wave packet is expected to be quite strong. Unfortunately, this sensitivity may weaken the experiment’s ability to measure the orientation of the neutrino mass hierarchy for currently allowed values of the wave-packet size. Here, we report both the JUNO experiment’s ability to determine the hierarchy orientation in the presence of a finite wave packet and its simultaneous sensitivity to size of the wave packet and the hierarchy. We find that wave-packet effects are relevant for the hierarchy determination up to nearly two orders of magnitude above the current experimental lower limit on the size, noting that there is no theoretical consensus on the expectation of this value. We also consider the effect in the context of other aspects of JUNO’s nominal three-neutrino oscillation measurement physics program and the prospect of future enhancements to sensitivity, including from precise measurements of $\mathrm{\Delta }{m}_{3l}^2$ and a near detector.

中文翻译：

---

JUNO 实验中的中微子退相干和质量等级

中微子波包在创建时的有限大小会影响其振荡概率。在这里，我们在基于核反应堆的实验 JUNO 的背景下考虑电子反中微子波包和退相干。鉴于 JUNO 的高预期统计数据 [$～100\mathrm{ķ}$IBD 事件 (${\overline{\nu }}_{e}p\to e^{+}n$)], 长基线 ($～53\mathrm{公里}$)，以及出色的能量分辨率 [$～0.03/\sqrt{{乙}_{\mathrm{可见}}(\mathrm{电子伏特})}$]，它对波包大小的敏感性预计会相当强。不幸的是，这种敏感性可能会削弱实验测量当前允许的波包大小值的中微子质量层次的方向的能力。在这里，我们报告了 JUNO 实验在存在有限波包的情况下确定层次方向的能力，以及它对波包大小和层次的同时敏感度。我们发现波包效应与层次确定相关，比当前实验的尺寸下限高出近两个数量级，并指出对该值的期望没有理论共识。$\mathrm{\Delta }{米}_{3l}^2$和近距探测器。