暗维与轴子宇宙的结合
The Dark Dimension meets the Axiverse
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中文总结 AI 辅助
该研究结合暗维与轴子宇宙场景，发现轴子塔可参与暗物质冻入产生，其能量注入的稀释效应能使暗维暗物质避开强宇宙学约束，还开发了评估塔碎裂的连续体方法。
中文摘要 AI 辅助
我们探索将暗维场景与轴子宇宙相结合的宇宙学意义。若规范 sector 实现于膜上，闭弦轴子的卡鲁扎-克莱因（KK）激发塔除了引力子激发塔外，还可在暗维中传播，这从两方面改变宇宙学：其一，若这些轴子塔中的任何一个与标准模型（SM）等离子体相互作用，可显著改变塔态宇宙丰度的冻入产生过程；当轴子衰变常数满足 $10^{12}\text{ GeV}\leq f_a \leq10^{16}\text{ GeV}$、 reheating 温度满足 $5\text{ MeV}\leq T_{\rm RH}\text{O}(1)\text{ GeV}$ 时，引力子和轴子塔的冻入可提供全部暗物质（DM）。其二，不同塔之间会发生碎裂并重新分配能量，每个塔在后期的能量占比由其相互作用决定；若存在 $N\neq1$ 个轴子塔，任何衰变塔注入 SM 的可见能量会被稀释 $N$ 倍，这种抑制为暗维暗物质如何避开排除最简单模型的强宇宙学约束提供了简单实现方式。在探索过程中，我们开发了一种评估塔碎裂的连续体方法，通过将问题简化为求积，为数值计算提供了洞见与帮助。
英文摘要
We explore the cosmological implications of combining dark dimension scenarios with an axiverse. If gauge sectors are realized on branes, towers of Kaluza-Klein (KK) excitations of closed string axions can propagate through the dark dimension in addition to the tower of graviton excitations. This modifies cosmology in two ways. First, if any of these axion towers interact with the standard model (SM) plasma, they can significantly alter the freeze-in production of the cosmological abundance of tower states. Freeze-in to graviton and axion towers can provide all of dark matter (DM) for an axion decay constant in $10^{12} \text{ GeV }\lesssim f_a\lesssim 10^{16}\,\text{ GeV }$ and reheating temperatures $5\text{ MeV }\lesssim T_{\rm RH} \lesssim O(1)\,\text{ GeV }$. Second, different towers fragment into each other and redistribute energy; each tower's fraction of energy at late times is fixed by their interactions. If there are $N\gg1$ axion towers, the energy visibly injected into the SM by any decaying tower is diluted by a factor of $N$. This suppression offers a simple realization of how dark dimension dark matter can avoid strong cosmological constraints which rule out the simplest models. In the process of this exploration we develop a continuum approach to evaluating tower fragmentation which offers insight and aids numerical calculations by reducing the problem to quadrature.
