超出$Δm^2$：中微子振荡中的绝对质量灵敏度
Beyond $Δm^2$: Absolute Mass Sensitivity in Neutrino Oscillations
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中文总结 AI 辅助
该研究突破中微子振荡仅测质量平方差的传统认知，通过波包处理推导次领头阶修正，发现JUNO实验可探测几百keV中微子质量，提供了互补的质量标度探测手段。
中文摘要 AI 辅助
传统观点认为，中微子振荡仅能测量质量平方差，无法测量中微子的绝对质量标度。不过，这一结论仅在展开参数$m_i/E$（即中微子质量$m_i$，$i=1,2,3$，与中微子能量$E$的比值）的领头阶成立。在次领头阶，振荡相位包含与$m_i^4-m_j^4 = Δm^2_{ij}(m_i^2+m_j^2)$成正比的项，因此对绝对质量标度敏感。本文中，我们采用波包处理方法并考虑中微子产生的运动学，推导了次领头阶修正。随后将该结果应用于反应堆反中微子，发现江门中微子实验（JUNO）对几百keV量级的中微子质量敏感。尽管其灵敏度不及β衰变、电子俘获和宇宙学的现有限制，但中微子振荡为中微子质量标度提供了一种新颖的互补探测手段，且对中微子质量的不同组合具有灵敏度。
英文摘要
Conventional wisdom says that neutrino oscillations measure only mass-squared differences and not the absolute neutrino mass scale. This is true, however, only at leading order in the expansion parameters $m_i/E$, the ratios of the neutrino masses $m_i$ ($i=1,2,3$) to the neutrino energy $E$. At next-to-leading order, the oscillation phase includes terms proportional to $m_i^4-m_j^4 = Δm^2_{ij}(m_i^2+m_j^2)$, and is therefore sensitive to the absolute mass scale. In this paper, we derive the next-to-leading-order corrections using a wave-packet treatment and taking into account the neutrino-production kinematics. We then apply this result to reactor antineutrinos and find that the JUNO experiment is sensitive to neutrino masses of a few hundred keV. While not competitive with existing bounds from beta decay, electron capture, and cosmology, neutrino oscillations provide a novel, complementary probe of the neutrino mass scale, with sensitivity to a different combination of neutrino masses.
