arXiv 0908.23052009-08astro-ph.COhep-ph

非高斯性作为暴胀热初始条件的一个特征

Non-Gaussianity as a signature of thermal initial condition of inflation

Suratna Das, Subhendra Mohanty

备注：: 17 RevTeX4 pages, 2 figures, One paragraph added in Introduction, No further changes made, Accepted for publication in PRD
发表信息：: Phys.Rev.D80:123537,2009
DOI：: 10.1103/PhysRevD.80.123537

摘要：

本文研究了单场暴胀中原初微扰的非高斯性，其中暴胀之前存在辐射时代。暴胀发生在辐射的能量密度降到相干标量场的势值以下时。我们计算了暴胀子涨落的两点、三点和四点关联函数的热平均值。三点函数与慢滚参数成正比，并且由于热浴的贡献，在$f_{NL}$中存在65至90倍的放大，并且我们得出结论，双谱在21 cm各向异性测量的可检测范围内。另一方面，由于热平均以及四点相关的热平均与两点函数的热平均的平方不同的事实，在这种情况下出现四点函数。由于这个事实，$τ_{NL}$与慢滚参数不成比例，并且可以大到-42。10阶四点相关的非高斯性也可以用21厘米背景观测来检测。我们得出结论，热膨胀的签名是一个大的三谱非高斯相比，双谱非高斯。

英文摘要：

We study non-Gaussianities in the primordial perturbations in single field inflation where there is radiation era prior to inflation. Inflation takes place when the energy density of radiation drops below the value of the potential of a coherent scalar field. We compute the thermal average of the two, three and four point correlation functions of inflaton fluctuations. The three point function is proportional to the slow roll parameters and there is an amplification in $f_{NL}$ by a factor of 65 to 90 due to the contribution of the thermal bath, and we conclude that the bispectrum is in the range of detectability with the 21-cm anisotropy measurements. The four point function on the other hand appears in this case due to the thermal averaging and the fact that thermal averaging of four-point correlation is not the same as the square of the thermal averaging of the two-point function. Due to this fact $τ_{NL}$ is not proportional to the slow-roll parameters and can be as large as -42. The non-Gaussianities in the four point correlation of the order 10 can also be detected by 21-cm background observations. We conclude that a signature of thermal inflatons is a large trispectrum non-Gaussianity compared to the bispectrum non-Gaussianity.

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