Curvature perturbation in multi-field inflation with non-minimal coupling
Curvature perturbation in multi-field inflation with non-minimal coupling
复制标题
非最小耦合多场膨胀中的曲率扰动
DOI：
10.1088/1475-7516/2012/07/039
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发表时间：
2012
影响因子：
6.4
通讯作者：
Misao Sasaki
中科院分区：
文献类型：
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作者：
Jonathan White;Masato Minamitsuji;Misao Sasaki
本文讨论了一个多场暴胀模型，其中一般所有场都与Ricci标量非极小耦合，并具有非正则动力学项。在Jordan和Einstein框架下计算了模型的背景演化和一阶扰动，并比较了各自的曲率扰动。我们确认，他们确实是不一样的，不像在单场的情况下，也是一个直接的后果，多场模型固有的等曲率扰动的差异。这个结果使我们得出结论，绝热性的概念是不不变的保角变换下。使用两个字段的例子，我们表明，即使在一个帧的演化是绝热的，这意味着曲率扰动是保守的超地平线尺度上，在一般情况下，在其他帧isocurvature扰动继续源曲率扰动。我们还发现，这是可能的，以实现一个特定的模型，其中曲率扰动在两个框架是保守的，但每个是不同的幅度。这些例子强调了曲率扰动本身，尽管是规范不变的，并不直接对应于一个可观测的。当考虑在系统中加入标准模型物质时，两个曲率扰动的不等价性也很重要。
In this paper we discuss a multi-field model of inflation in which generally all fields are non-minimally coupled to the Ricci scalar and have non-canonical kinetic terms. The background evolution and first-order perturbations for the model are evaluated in both the Jordan and Einstein frames, and the respective curvature perturbations compared. We confirm that they are indeed not the same-unlike in the single-field case-and also that the difference is a direct consequence of the isocurvature perturbations inherent to multi-field models. This result leads us to conclude that the notion of adiabaticity is not invariant under conformal transformations. Using a two-field example we show that even if in one frame the evolution is adiabatic, meaning that the curvature perturbation is conserved on super-horizon scales, in general in the other frame isocurvature perturbations continue to source the curvature perturbation. We also find that it is possible to realise a particular model in which curvature perturbations in both frames are conserved but with each being of different magnitude. These examples highlight that the curvature perturbation itself, despite being gauge-invariant, does not correspond directly to an observable. The non-equivalence of the two curvature perturbations would also be important when considering the addition of Standard Model matter into the system.