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arXiv 1604.06017astro-ph.COgr-qchep-phhep-th
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随机暴胀中的临界场数

Critical Number of Fields in Stochastic Inflation

Vincent Vennin, Hooshyar Assadullahi, Hassan Firouzjahi, Mahdiyar Noorbala, David Wands

摘要:

在一般的情况下,通货膨胀与多个领域的随机效应进行了研究。首次通过时间技术被用来计算暴胀$e$ -折叠数的统计矩,这些统计矩通过随机$δN$形式主义产生原始曲率扰动的所有关联函数。字段的数量是一个关键参数。当有两个以上的场驱动暴胀时,探索任意大的势场区域的概率变得不为零。$e$ -折叠的平均数可以是无限的,这取决于场的数量;对于平台电位,即使有一个场也会发生这种情况。在这种情况下,曲率扰动的关联函数是无穷大的。然而,如果在大能量或场值下添加反射(或吸收)壁,则它们可以被正则化。结果被发现是独立的壁的确切位置,因此,这个过程是定义良好的广泛的截止,高于或低于普朗克尺度。最后,我们表明,与单场设置,多场模型可以产生大的随机校正,即使在次普朗克能量,打开有趣的前景探测宇宙学波动的量子效应。

英文摘要:

Stochastic effects in generic scenarios of inflation with multiple fields are investigated. First passage time techniques are employed to calculate the statistical moments of the number of inflationary $e$-folds, which give rise to all correlation functions of primordial curvature perturbations through the stochastic $δN$ formalism. The number of fields is a critical parameter. The probability of exploring arbitrarily large-field regions of the potential becomes non-vanishing when more than two fields are driving inflation. The mean number of $e$-folds can be infinite, depending on the number of fields; for plateau potentials, this occurs even with one field. In such cases, correlation functions of curvature perturbations are infinite. They can, however, be regularised if a reflecting (or absorbing) wall is added at large energy or field value. The results are found to be independent of the exact location of the wall and this procedure is, therefore, well-defined for a wide range of cutoffs, above or below the Planck scale. Finally, we show that, contrary to single-field setups, multi-field models can yield large stochastic corrections even at sub-Planckian energy, opening interesting prospects for probing quantum effects on cosmological fluctuations.

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