We show, both analytically and numerically, that non-Gaussian tails in the probability density function of curvature perturbations arise in ultra-slow-roll inflation from the δN formalism, without invoking stochastic inflation. Previously reported discrepancies between both approaches are a consequence of not correctly accounting for momentum perturbations. Once they are taken into account, both approaches agree to an excellent degree. The shape of the tail depends strongly on the phase space of inflation.

中文翻译：

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无随机膨胀的非高斯尾部


我们从分析和数值上表明，曲率扰动的概率密度函数中的非高斯尾部是在 δN 形式主义的超慢滚动膨胀中产生的，而没有调用随机膨胀。以前报道的两种方法之间的差异是由于没有正确考虑动量扰动的结果。一旦将它们考虑在内，这两种方法都同意在极好的程度上。尾巴的形状在很大程度上取决于膨胀的相空间。