来自热弛豫的相干与随机轴子暗物质
Coherent and Stochastic Axion Dark Matter from Thermal Relaxation
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中文总结 AI 辅助
该研究探讨轴子暗物质的热弛豫过程，推导膨胀等离子体中相干场与随机动量模式的演化关系，发现热弛豫决定轴子暗物质的组成、动量分布与输运结构，弱耦合实现可满足暗物质相关观测约束。
中文摘要 AI 辅助
轴子被驱动至热极小值时，未必会保持为相干凝聚态。我们推导了膨胀等离子体中场平均值的耦合衰减与随机动量模式的产生过程。一个与动量相关的光学深度将每个模式划分为相干功率与玻色占据态，使标准错定、部分弛豫与随机产生处于同一动力学关系中。有限的时空响应会抑制高动量模式的产生，因此在固定质量与浴温下，随机遗迹的平均动量低于平衡态粒子，自由流长度也更短。弱耦合实现可产生暗物质丰度，减少继承的相干等曲率，并将产生关联限制在无碰撞传播移除的尺度上。因此，热弛豫决定了轴子暗物质的组成、动量分布与输运结构。
英文摘要
An axion driven toward a thermal minimum need not remain a coherent condensate. We derive the coupled attenuation of the field mean and production of stochastic momentum modes in an expanding plasma. A single momentum dependent optical depth partitions every mode between coherent power and Bose occupation, placing standard misalignment, partial relaxation, and stochastic production in one dynamical relation. Finite spatial and temporal response suppresses high momentum production, so the stochastic relic has lower mean momentum and a shorter free streaming length than an equilibrium population at fixed mass and bath temperature. A weakly coupled realization produces the dark matter abundance, reduces inherited coherent isocurvature, and confines production correlations to scales removed by collisionless propagation. Thermal relaxation therefore determines the composition, momentum distribution, and transported structure of axion dark matter.
