具有非真空初始态的各向异性狄拉克-玻恩-因费尔德暴胀：原初微扰、非高斯性及观测约束
Anisotropic Dirac-Born-Infeld Inflation with Non-Vacuum Initial States: Primordial Perturbations, Non-Gaussianity, and Observational Constraints
AI总结：
研究具有非真空初始态的各向异性狄拉克-玻恩-因费尔德暴胀模型，利用ADM形式展开作用量，通过慢滚部分和博戈留波夫系数纳入相关影响，经数值分析和与观测数据集比较，确定模型参数空间可行区域，表明该情形在合适参数范围可与相关约束兼容。
AI中文摘要：
我们研究了具有非真空初始态的各向异性狄拉克-玻恩-因费尔德（DBI）暴胀模型中的线性和非线性原初微扰。利用阿尔诺维特-德塞-米斯纳（ADM）形式，将作用量展开到曲率微扰的二阶和三阶，导出相应的标量和张量功率谱、双谱以及等边非线性参数\(f_{NL}^{\mathrm{equil}}\)。通过慢滚部分和博戈留波夫系数纳入各向异性修正和非邦奇-戴维斯（non-BD）初始条件的影响。在数值分析中，考虑中间膨胀情形及激发态占据数\(N_k\)的唯象假设。通过将模型预测与近期观测数据集比较，确定模型参数空间中可观测的可行区域。我们的分析表明，具有非真空初始条件的各向异性DBI情形在各向异性参数\(c\)和初始态参数\(N_{k,0}\)的合适范围内，可与当前对标量谱指数、张量与标量比及等边非高斯性的约束兼容。
英文摘要：
We investigate linear and nonlinear primordial perturbations in an anisotropic Dirac-Born-Infeld (DBI) inflationary model with a non-vacuum initial state. Using the Arnowitt-Deser- Misner (ADM) formalism, we expand the action up to second and third order in the curvature perturbation and derive the corresponding scalar and tensor power spectra, as well as the bispectrum and the equilateral non-linearity parameter \(f_{NL}^{\mathrm{equil}}\). The effects of anisotropic corrections and non-Bunch-Davies (non-BD) initial conditions are incorporated through the slow-roll sector and Bogoliubov coefficients. For the numerical analysis, we consider an intermediate expansion scenario together with a phenomenological ansatz for the excited-state occupation number \(N_k\). By comparing the model predictions with recent observational datasets, including Planck2018 TT, TE, EE + lowE + lensing + BK18 + BAO and DESI+CMB+DESY5 data, we identify observationally viable regions in the parameter space of the model. Our analysis indicates that the anisotropic DBI scenario with non-vacuum initial conditions can remain compatible with current constraints on the scalar spectral index, tensor-to-scalar ratio, and equilateral non-Gaussianity for suitable ranges of the anisotropy parameter \(c\) and the initial-state parameter \(N_{k,0}\).
