动力学编织暗能量中动量交换导致的幻影分界线穿越与结构增长抑制
Phantom-divide crossing and suppressed structure growth in kinetically braided dark energy with momentum exchange
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中文总结 AI 辅助
该研究构建线性稳定标量场模型，实现暗能量状态方程穿越与 CDM 结构增长抑制，通过改进 CLASS 计算揭示辐射-物质相等附近的瞬态编织特征，为模型似然分析提供依据。
中文摘要 AI 辅助
我们构建了一个线性稳定的标量场模型，该模型同时实现了暗能量状态方程从$w_{\rm DE}<-1$向上穿越到$w_{\rm DE}>-1$，以及冷暗物质（CDM）领域引力聚结减弱。指数势破坏移位对称性，驱动背景从稳定幻影相向非幻影 regime 演化，而纯动量转移相互作用增加了 CDM 的动力学惯性，同时不改变其背景稀释规律。我们推导了背景和线性扰动方程，建立了无鬼场和拉普拉斯稳定性条件。对于哈勃半径深处的扰动，即准静态近似适用的区域，CDM 的有效引力耦合可低于牛顿常数，从而抑制晚期增长和小尺度物质功率，而重子耦合因伽利略编织仍保持增强。包含标量场扰动和完整玻尔兹曼层级的改进 CLASS 计算，揭示了辐射-物质相等附近的瞬态编织特征。在本文研究的代表性稳定解中，这些特征包括数值探测到的最低波数处物质功率增强，以及多极范围$2\leq\ell\leq30$内的 CMB 温度功率降低。我们还发现声学尺度和第一个温度峰位置的微小偏移。这些结果为该模型的完整似然分析提供了动机。
英文摘要
We construct a linearly stable scalar-field model that realizes both an upward crossing of the dark-energy equation of state, from $w_{\rm DE}<-1$ to $w_{\rm DE}>-1$, and weakened gravitational clustering in the cold dark matter (CDM) sector. An exponential potential breaks shift symmetry and drives the background from a stable phantom phase toward the nonphantom regime, while a pure momentum-transfer interaction increases the dynamical inertia of CDM without altering its background dilution law. We derive the background and linear perturbation equations and establish the no-ghost and Laplacian-stability conditions. For perturbations deep inside the Hubble radius, where the quasi-static approximation applies, the effective gravitational coupling for CDM can fall below Newton's constant, suppressing late-time growth and small-scale matter power, while the baryonic coupling remains enhanced by Galileon braiding. A modified CLASS calculation, including the scalar-field perturbation and the full Boltzmann hierarchies, reveals signatures of transient braiding around radiation--matter equality. For the representative stable solutions studied here, these signatures include an enhancement of matter power toward the lowest wavenumbers probed numerically and a reduction of CMB temperature power over the multipole range $2\leq\ell\leq30$. We also find small shifts in the acoustic scale and the position of the first temperature peak. These results motivate a full likelihood analysis of the model.
