Implications of the Planck bispectrum constraints for the primordial trispectrum
Implications of the Planck bispectrum constraints for the primordial trispectrum
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DOI：
10.1209/0295-5075/103/19001
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发表时间：
2013-06
期刊：
影响因子：
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通讯作者：
C. Byrnes;Sami Nurmi;G. Tasinato;D. Wands
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文献类型：
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作者：
C. Byrnes;Sami Nurmi;G. Tasinato;D. Wands
新的普朗克约束的局部双谱参数是约105倍，比目前的约束的三谱参数，这意味着允许的数值的二阶和三阶项的微扰展开的曲率微扰是可比的。我们表明，这是一个后果，如果是足够大的检测，那么它会引起一个大的变化之间的可观测值和它的值在一个更大的膨胀体积。即使在暴胀开始和哈勃视界的视界交叉之间只有一些额外的e折叠，一个显著的大的意味着不太可能像它当前的约束一样小，不管它的真实背景值如何。这个结果是非常一般的，它保持不管有多少场贡献的曲率扰动。我们还将这一结果推广到其他形状的非高斯性，超出了本地模型。我们证明了三点函数在压缩极限中的方差由四点函数的压缩极限的平方从下有界。
The new Planck constraints on the local bispectrum parameter are about 105 times tighter than the current constraints on the trispectrum parameter , which means that the allowed numerical values of the second-and third-order terms in the perturbative expansion of the curvature perturbation are comparable. We show that a consequence of this is that if is large enough to be detectable, then it will induce a large variation between the observable value of and its value in a larger inflated volume. Even if there were only a few extra e-foldings between the beginning of inflation and horizon crossing of our Hubble horizon, an observably large means that is unlikely to be as small as its current constraint, regardless of its true background value. This result is very general, it holds regardless of how many fields contributed to the curvature perturbation. We also generalise this result to other shapes of non-Gaussianity, beyond the local model. We show that the variance of the 3-point function in the squeezed limit is bounded from below by the square of the squeezed limit of the 4-point function.