A zero initial velocity of the axion field is assumed in the conventional misalignment mechanism. We propose an alternative scenario where the initial velocity is nonzero, which may arise from an explicit breaking of the PQ symmetry in the early Universe. We demonstrate that, depending on the specifics about the initial velocity and the time order of the PQ symmetry breaking vs. inflation, this new scenario can alter the conventional prediction for the axion relic abundance in different, potentially significant ways. As a result, new viable parameter regions for axion dark matter may open up.

中文翻译：

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轴子错位机制的新观点

在传统的未对准机制中假设轴子场的初始速度为零。我们提出了一种初始速度非零的替代方案，这可能是由于早期宇宙中 PQ 对称性的显式破坏引起的。我们证明，根据初始速度和 PQ 对称性破坏与膨胀的时间顺序的具体情况，这种新情况可以以不同的、潜在的重要方式改变对轴子遗迹丰度的传统预测。因此，轴子暗物质的新可行参数区域可能会开放。