轴子-WIMP相互作用产生的自然幻影穿越
Natural Phantom Crossing from Axion-WIMP Interactions
AI总结：
该研究构建了由N种费米子及ℤ_N对称性关联的热DM与轴子DE相互作用模型，避免轴子势不稳定，实现无鬼场的晚期幻影穿越，给出类DESI解并探讨其对DM搜寻的意义。
AI中文摘要：
我们构建了一个技术上自然的模型，其中热暗物质（DM）与轴子暗能量（DE）相互作用，产生表观的晚期幻影分岔穿越。轴子与弱相互作用大质量粒子（WIMP）的直接耦合通常会在辐射层面使超轻轴子势不稳定，我们通过由循环ℤ_N对称性关联的N种费米子物种避免了这一问题，该对称性将主导Coleman-Weinberg势投影到指数抑制的N次谐波上。尽管微观理论保留ℤ_N对称性，但轴子依赖的WIMP质量会产生不等的平衡丰度，这些丰度在退耦时会印在宇宙遗迹态上，从而自发打破对称性。由此产生的遗迹分布保留了初始轴子值的记忆，并产生未被抑制的有限密度势，该势在早期将轴子场固定。随着WIMP密度稀释，轴子会向其禁闭势的最小值滚动，在晚期将能量从DE转移到DM。若观测者假设各组分分别守恒，会推断出有效状态方程穿越到-1以下，且无鬼场或零能量条件违反。我们给出了一个类DESI幻影穿越的说明性宇宙学解，以及结构增长的百分级抑制，并讨论了WIMP多重性和遗迹分布对DM搜寻的意义。
英文摘要：
We construct a technically natural model in which thermal dark matter (DM) interacts with axion dark energy (DE) and produces an apparent late-time crossing of the phantom divide. A direct axion coupling to weakly-interacting massive particles (WIMPs) would ordinarily radiatively destabilize the ultralight axion potential. We avoid this issue through $N$ fermion species related by a cyclic $\mathbb{Z}_N$ symmetry, which projects the leading Coleman-Weinberg potential onto the exponentially suppressed $N$th harmonic. Although the microscopic theory preserves $\mathbb{Z}_N$, the axion-dependent WIMP masses generate unequal equilibrium abundances that freeze-out imprints on the cosmological relic state, thereby breaking the symmetry spontaneously. The resulting relic distribution retains a memory of the initial axion value and generates an unsuppressed finite-density potential that holds the field fixed at early times. As the WIMP density dilutes, the axion rolls toward the minimum of its confining potential, transferring energy from DE to DM at late times. An observer assuming separately conserved components then infers an effective equation of state that crosses below $-1$, without ghosts or violation of the null-energy condition. We present an illustrative cosmological solution with a DESI-like phantom crossing and percent-level suppression of structure growth, and discuss the implications of the WIMP multiplicity and relic distribution for DM searches.
