Simple method for determining asymptotic states of fast neutrino-flavor conversion
Simple method for determining asymptotic states of fast neutrino-flavor conversion
复制标题
确定快速中微子-味转换渐近态的简单方法
DOI：
10.1103/physrevd.107.103022
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发表时间：
2023
影响因子：
5
通讯作者：
Nagakura Hiroki
中科院分区：
文献类型：
--
作者：
Zaizen Masamichi;Nagakura Hiroki
中微子-中微子前向散射可能会在核心塌缩超新星（CCSNe）和双中子星合并（BNSM）等天体物理地点的致密中微子气体中引起集体中微子振荡。在本文中，我们通过稳定性分析和周期性边界条件的局部模拟，对快速中微子味道转换（FFC）进行了详细研究，特别关注渐近态。我们发现渐近态可以通过 FFC 的两个关键属性来表征：(1) 每种中微子的轻子数守恒，以及 (2) 空间或时间平均分布中 ELN（电子中微子-轻子数）-XLN（重轻子数）角交叉的消失。最初具有正（负）ELN-XLN 密度的系统在负（正）ELN-XLN 角度方向上达到风味均分，另一部分对其进行补偿以保持守恒定律。 FFC 的这些特性提供了一种近似方案，可以确定中微子在渐近态下的生存概率，而无需求解量子动力学方程。我们还证明，对于相同的 ELN-XLN 中微子，味道转换的总量可能会随着物种相关的中微子分布而变化。我们的结果表明，即使是浅或窄的 ELN 角交叉也有能力通过 FFC 在中微子更丰富的角方向上打乱大量中微子，这表明需要在 CCSN 和 BNSM 的建模中考虑 FFC 的影响。
Neutrino-neutrino forward scatterings potentially induce collective neutrino oscillation in dense neutrino gases in astrophysical sites such as core-collapse supernovae (CCSNe) and binary neutron star mergers (BNSMs). In this paper, we present a detailed study of fast neutrino-flavor conversion (FFC), paying special attention to asymptotic states, by means of stability analysis and local simulations with a periodic boundary condition. We find that asymptotic states can be characterized by two key properties of FFC: (1) the conservation of lepton number for each flavor of neutrinos and (2) the disappearance of ELN (electron neutrino-lepton number)-XLN (heavy-leptonic one) angular crossings in the spatial- or time-averaged distributions. The system that initially has the positive (negative) ELN-XLN density reaches a flavor equipartition in the negative (positive) ELN-XLN angular directions, and the other part compensates it to preserve the conservation laws. These properties of FFCs offer an approximate scheme determining the survival probability of neutrinos in asymptotic states without solving quantum kinetic equations. We also demonstrate that the total amount of flavor conversion can vary with species-dependent neutrino distributions for identical ELN-XLN ones. Our results suggest that even shallow or narrow ELN angular crossings have the ability to shuffle large amount of neutrinos among flavors through FFC in the angular directions where neutrinos are more abundant, indicating the need for including the effects of FFCs in the modeling of CCSN and BNSM.