轴子-膨胀子暗能量：动力系统与贝叶斯推断分析

中文摘要 AI 辅助

我们启动了对由超引力和弦紧化普遍激发的弯曲场空间度规所支配的轴子-膨胀子系统的系统性宇宙学研究。标量部门由一个沿渐近指数势演化的轻标量膨胀子场和一个跨越基本平坦方向的赝标量场组成，二者通过指数场空间度规进行动力学耦合。通过引入包含多项式因子的广义Albrecht-Skordis势来纳入对渐近区域的偏离。利用动力系统方法、数值演化以及贝叶斯推断，我们使用Ia型超新星（SNe Ia）、重子声学振荡（BAO）和普朗克2018距离先验数据来约束该模型。我们识别出一个参数简并性，表明更陡的势需要更强的场空间动力学耦合以维持晚期宇宙加速。最后，联合似然分析揭示，尽管该模型成功解释了暗能量动力学，但当前观测仅使其在统计上略微优于ΛCDM模型。

英文摘要

We initiate a systematic cosmological investigation of an axio-dilaton system governed by a curved field-space metric as generically motivated by supergravity and string compactifications. The scalar sector consists of a light scalar dilaton field evolving along an asymptotically exponential potential and a pseudoscalar field spanning an essentially flat direction, kinetically coupled through an exponential field-space metric. Deviations from the asymptotic regime are incorporated by introducing a generalised Albrecht-Skordis potential containing a polynomial factor. Utilising a dynamical systems approach alongside numerical evolution and Bayesian inference, we constrain the model using Type Ia Supernovae (SNe Ia), Baryon Acoustic Oscillations (BAO) and Planck 2018 distance-prior data. We identify a parameter degeneracy indicating that steeper potentials demand stronger field-space kinetic couplings to sustain late-time cosmic acceleration. Finally, a joint likelihood analysis reveals that while the model successfully accounts for dark energy dynamics, it is only slightly statistically favoured over $Λ$CDM by current observations.

发表机构

• University of Cambridge（剑桥大学）
• Universidad Nacional Autónoma de México（墨西哥国立自治大学）
• New York University Abu Dhabi（阿布扎比纽约大学）

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