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arXiv 1802.04290astro-ph.COgr-qchep-th
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G-暴胀中的张量和标量观测量

Reconciling tensor and scalar observables in G-inflation

Héctor Ramírez, Samuel Passaglia, Hayato Motohashi, Wayne Hu, Olga Mena

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Published version
发表信息：
JCAP04(2018)039
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摘要：

作为暴胀模型的简单$m^2ϕ^2$势，由于张量与标量之比$r$和标量谱指数$n_s$的测量受到限制，正面临越来越大的压力。在Horndeski作用量的背景下，立方伽利略相互作用可能会调和观测值。然而，我们表明，这不能实现只有一个恒定的伽利略质量尺度，因为相互作用关闭太慢，也导致梯度不稳定性后，通货膨胀结束。允许更快的跃迁可以调和观测值，但适度地破坏慢滚近似，导致倾斜$α_s$的相对较大和负的运行，其可以是$n_s-1$阶。我们表明，CMB和大尺度结构尺度上的观测值可以准确地预测使用优化的慢卷方法，而不是传统的慢卷扩展。$|α_s|$的上限是$r\gtrsim 0.005$的下限，相反，给定的$r$是$|α_s|$的下限，这两者都可能通过下一代CMB和大尺度结构勘测观察到。

英文摘要：

The simple $m^2ϕ^2$ potential as an inflationary model is coming under increasing tension with limits on the tensor-to-scalar ratio $r$ and measurements of the scalar spectral index $n_s$. Cubic Galileon interactions in the context of the Horndeski action can potentially reconcile the observables. However, we show that this cannot be achieved with only a constant Galileon mass scale because the interactions turn off too slowly, leading also to gradient instabilities after inflation ends. Allowing for a more rapid transition can reconcile the observables but moderately breaks the slow-roll approximation leading to a relatively large and negative running of the tilt $α_s$ that can be of order $n_s-1$. We show that the observables on CMB and large scale structure scales can be predicted accurately using the optimized slow-roll approach instead of the traditional slow-roll expansion. Upper limits on $|α_s|$ place a lower bound of $r\gtrsim 0.005$ and conversely a given $r$ places a lower bound on $|α_s|$, both of which are potentially observable with next generation CMB and large scale structure surveys.

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