发表机构
University of Tokyo; Kavli Institute for the Physics and Mathematics of the Universe（东京大学; 卡弗里宇宙物理学与数学研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
提出一种由原始不对称性产生、经重组形成暗原子并因振荡而近对称的玻色子-费米子暗物质模型，其暗辐射贡献ΔNeff≈0.05-0.07可被未来CMB观测检验。
AI 中文摘要
我们提出了一种简单的玻色子-费米子原子暗物质情景，其中暗物质丰度起源于原始粒子-反粒子不对称性。暗扇区由一个复标量场和一个狄拉克费米子场组成，它们在一个未破缺的U(1)$_D$规范对称性下携带相反的电荷。它们的不对称性通过暴胀子衰变产生的重马约拉纳费米子的CP破坏衰变非热产生，与可见扇区中的非热轻子生成机制密切类似。对称分量有效地湮灭为无质量暗光子，而存活的标量和费米子种群无法相互湮灭，反而重新结合成中性的玻色子-费米子暗原子。值得注意的是，负责产生原始不对称性的相同相互作用在重组后诱导原子-反原子振荡，因此尽管暗物质起源于不对称，但当今的暗物质可以近似对称。残余的电离分量或足够延展的暗原子也可以产生显著的暗物质自相互作用，可能对暗物质晕的形成和结构留下可观测的印记，并提供对暗扇区的补充宇宙学和天体物理学探测手段。无质量暗光子作为暗辐射存留，对于此处考虑的热历史，产生特征性贡献$\Delta N_{\rm eff}\simeq0.05-0.07$。这一预测位于未来精密CMB观测的探测范围内，为该情景提供了直接的宇宙学检验。
英文摘要
We propose a simple scenario of boson-fermion atomic dark matter, in which the dark matter abundance originates from a primordial particle-antiparticle asymmetry. The dark sector consists of a complex scalar and a Dirac fermion carrying opposite charges under an unbroken U(1)$_D$ gauge symmetry. Their asymmetries are generated non-thermally through the CP-violating decays of heavy Majorana fermions produced by inflaton decay, in close analogy with non-thermal leptogenesis in the visible sector. The symmetric components efficiently annihilate into massless dark photons, while the surviving scalar and fermion populations cannot annihilate with each other and instead recombine into neutral boson-fermion dark atoms. Remarkably, the same interactions responsible for generating the primordial asymmetry induce atom-antiatom oscillations after recombination, so that the present-day dark matter can be approximately symmetric despite its asymmetric origin. Residual ionized components or sufficiently extended dark atoms can also give rise to appreciable dark-matter self-interactions, potentially leaving observable imprints on the formation and structure of dark matter halos and offering complementary cosmological and astrophysical probes of the dark sector. The massless dark photon survives as dark radiation, yielding a characteristic contribution $ΔN_{\rm eff}\simeq0.05-0.07$ for the thermal history considered here. This prediction lies within the reach of future precision CMB observations, providing a direct cosmological test of the scenario.
Comments15 pages, 1 figure
