Non-Gaussianity from the second-order cosmological perturbation
Non-Gaussianity from the second-order cosmological perturbation
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DOI：
10.1103/physrevd.71.123508
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发表时间：
2005-02
影响因子：
5
通讯作者：
D. Lyth;Yeinzon Rodriguez Department of Physics Lancaster University-Yeinzon-Rodriguez-Department-of-Physics-Lancaster-102312475;C. D. I. U. A. Narino
中科院分区：
文献类型：
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作者：
D. Lyth;Yeinzon Rodriguez Department of Physics Lancaster University-Yeinzon-Rodriguez-Department-of-Physics-Lancaster-102312475;C. D. I. U. A. Narino
文献中已经给出了几个被描述为二阶曲率微扰的守恒量和/或规范不变量。我们回顾了在原始曲率微扰{Zeta}中产生二阶非高斯性的各种场景，首次采用了统一的符号，并集中在双谱的归一化f{subNL}上。当{Zeta}在地平线离开后几次首次出现哈勃时，|f{subNL}|远远小于1，因此可以忽略不计。此后，只要压力是能量密度(绝热压力)的唯一函数，{Zeta}(从而f{subNL})是守恒的。非绝热压力可能只来自场的影响，而不是指向膨胀轨迹的场，而场在膨胀时是轻的(轻的非膨胀场)。在单组分膨胀过程中，f{subNL}是恒定的，但多组分膨胀可能会产生垂直条形f{subNL}垂直条形{近似}1或更大。预热只有在非典型情况下才会影响f{SUB NL}，因为它涉及轻的非膨胀场。最简单的曲率情形通常给出f{subNL}<；-1或f{subNL}=+5/4。非均匀再加热情形可以给出f{subNL}的很大范围的值。除非有检测到，否则观测最终可以提供极限垂直条形f{subNL}垂直条形或近似。在哪个水平上，使用二阶理论计算精确的观测极限将是至关重要的。
Several conserved and/or gauge-invariant quantities described as the second-order curvature perturbation have been given in the literature. We revisit various scenarios for the generation of second-order non-Gaussianity in the primordial curvature perturbation {zeta}, employing for the first time a unified notation and focusing on the normalization f{sub NL} of the bispectrum. When {zeta} first appears a few Hubble times after horizon exit, |f{sub NL}| is much less than 1 and is, therefore, negligible. Thereafter {zeta} (and hence f{sub NL}) is conserved as long as the pressure is a unique function of energy density (adiabatic pressure). Nonadiabatic pressure comes presumably only from the effect of fields, other than the one pointing along the inflationary trajectory, which are light during inflation ('light noninflaton fields'). During single-component inflation f{sub NL} is constant, but multicomponent inflation might generate vertical bar f{sub NL} vertical bar {approx}1 or bigger. Preheating can affect f{sub NL} only in atypical scenarios where it involves light noninflaton fields. The simplest curvaton scenario typically gives f{sub NL}<<-1 or f{sub NL}=+5/4. The inhomogeneous reheating scenario can give a wide range of values for f{sub NL}. Unless there is a detection, observation can eventually provide a limit vertical bar f{sub NL} vertical barmore » or approx. 1, at which level it will be crucial to calculate the precise observational limit using second-order theory.« less