发表机构
Center for Particle Cosmology, Department of Physics and Astronomy, University of Pennsylvania; Departamento de Física, FCFM, Universidad de Chile; Centro de Ciencias Exactas, Facultad de Ciencias, Universidad del Bío-Bío（宾夕法尼亚大学物理与天文学系粒子宇宙学中心; 智利大学理学院和师范学院物理系; 比奥比奥大学理学院精确科学中心）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文推导了不等声速两场暴胀系统的正则模，求解功率谱与双谱，揭示声速比对功率增强和振荡的影响，并精确处理混合参数下的对撞机信号。
AI 中文摘要
我们推导了具有任意常数二次混合以及曲率和等曲率扰动分别具有不等声速 $c_\varphi$ 和 $c_\sigma$ 的两场暴胀系统的正则归一化模。拉普拉斯表示将耦合动力学简化为二阶Heun方程，并给出了任意混合参数和熵质量值下精确的晚期曲率功率谱。声速比 $r_c=c_\sigma/c_\varphi$ 控制两个声视界之间的分离。在固定的非零混合且 $r_c\ll1$ 时，功率表现出幂律增强、随 $\ln^2(1/r_c)$ 增长或随 $\ln r_c$ 有界振荡，具体取决于质量和混合。对于 $r_c\gg1$，在固定质量和混合下，对未混合谱的修正随 $\ln r_c/r_c^2$ 消失。利用相同的归一化模，我们计算了三种代表性三次相互作用下的树级双谱，其中混合参数被精确处理。对于重熵场，不等声速修改了对撞机振幅和相位，同时保留了由最终熵质量设定的严格压缩频率。功率归一化振幅可随 $r_c$ 非单调变化，且声速层级可延迟达到该渐近区域。
英文摘要
We derive the canonically normalized modes of a two-field inflationary system with arbitrary constant quadratic mixing and unequal sound speeds $c_φ$ and $c_σ$ for the curvature and isocurvature perturbations, respectively. A Laplace representation reduces the coupled dynamics to a second-order Heun equation and gives the exact late-time curvature power spectrum for arbitrary values of the mixing parameter and entropy mass. The sound-speed ratio $r_c=c_σ/c_φ$ controls the separation between the two sound horizons. At fixed nonzero mixing and $r_c\ll1$, the power exhibits power-law enhancement, growth as $\ln^2(1/r_c)$, or bounded oscillations in $\ln r_c$, depending on the mass and mixing. For $r_c\gg1$, the correction to the unmixed spectrum vanishes as $\ln r_c/r_c^2$ at fixed mass and mixing. Using the same normalized modes, we compute the tree-level bispectrum for three representative cubic interactions, with the mixing parameter treated exactly. For heavy entropy fields, unequal speeds modify the collider amplitude and phase while preserving the strict squeezed frequency set by the final entropy mass. The power-normalized amplitude can vary nonmonotonically with $r_c$, and a sound-speed hierarchy can delay the approach to this asymptotic regime.
Comments60 pp. 7 figures
