发表机构
Niels Bohr International Academy and DARK, Niels Bohr Institute, University of Copenhagen（哥本哈根大学尼尔斯·玻尔研究所及尼尔斯·玻尔国际学院与DARK中心）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究通过半圆环二维模型分析核心坍缩超新星中，LESA存在时的中微子味转换，发现其可使LESA偶极增强5%-10%，且方向依赖的味转换会影响全局中微子不对称性与流体动力学不稳定性发展。
AI 中文摘要
我们在半圆环区域求解中微子运动方程，考虑两个空间维度。在圆环内任意位置，中微子动量由极角分布、两个有效方位角和能量分布表征。我们探究在核心坍缩超新星停滞激波阶段，中微子驱动的流体动力学不稳定性LESA（即轻子数发射自维持不对称性）存在时，中微子脱离物质时如何改变其味。在我们的模型中，LESA导致圆环北部区域的电子中微子（νₑ）和南部区域的反电子中微子（ν̄ₑ）过量。在圆环的电子中微子缺失的南部区域出现νₑ-ν̄ₑ角分布交叉，且整个圆环内存在νₑ-νₓ和ν̄ₑ-ν̄ₓ的能量分布交叉。我们发现，碰撞不稳定性在中微子脱离前驱动味转换，快不稳定性在圆环南部区域显著，慢不稳定性则主导其他区域。味转换在南部区域最有效，使LESA偶极增强5%-10%，且与中微子质量顺序无关。我们的发现表明，方向依赖的味转换可能对核心坍缩超新星中全局中微子不对称性和流体动力学不稳定性的发展产生影响。
英文摘要
We solve the neutrino equations of motion in a half annulus, accounting for two spatial dimensions. At any location in the annulus, the neutrino momentum is characterized by a polar-angle distribution, two effective azimuthal angles, and an energy distribution. We explore how neutrinos change their flavor while decoupling from matter in the presence of the neutrino-driven hydrodynamical instability LESA (i.e., the Lepton-number Emission Self-sustained Asymmetry) during the stalled-shock phase of a core-collapse supernova. In our setup, LESA is responsible for an excess of $ν_e$'s ($\barν_e$'s) in the Northern (Southern) region of the annulus. Crossings in the $ν_e$-$\barν_e$ angular distributions appear in the ELN-depleted Southern region of the annulus, while crossings in the energy distributions of $ν_e$-$ν_x$ and $\barν_e$-$\barν_x$ are present throughout the annulus. We find that collisional instabilities drive flavor conversion just before neutrino decoupling, fast instabilities are prominent in the Southern region of the annulus, and slow instabilities dominate otherwise. Flavor conversion is most efficient in the Southern region and is responsible for a $5$-$10\%$ enhancement of the LESA dipole, independent of the neutrino-mass ordering. Our findings suggest that direction-dependent flavor conversion can have implications for the development of global neutrino asymmetries and hydrodynamical instabilities in core-collapse supernovae.
Comments26 pages, 22 figures, and 3 appendices
