In recent years, the detection of gravitational waves by LIGO and PTA collaborations have raised the intriguing possibility of excess matter power at small scales. Such an increase can be achieved by ultra slow roll (USR) phase during inflationary epoch. We constrain excess power over small scales within the framework of such models using cosmological datasets, particularly of CMB anisotropies and Lyman-α. We parameterize the USR phase in terms of the e-fold at the onset of USR (counted from the end of inflation) N̅₁ and the duration of USR phase Δ N. The former dictates the scale of enhancement in the primordial power spectrum, while the latter determines the amplitude of such an enhancement. From a joint dataset of CMB and galaxy surveys, we obtain N̅₁ ≲ 45 with no bound on Δ N. This in turn implies that the scales over which the power spectrum can deviate significantly from the nearly scale invariant behavior of a typical slow-roll model is k ≳1 Mpc^-1. On the other hand, the Lyman-α data is sensitive to baryonic power spectrum along the line of sight. We consider a semi-analytic theoretical method and high spectral-resolution Lyman-α data to constrain the model. The Lyman-α data limits both the USR parameters: N̅₁ ≲ 41 and Δ N ≲ 0.4. This constrains the amplitude of the power spectrum enhancement to be less than a factor of hundred over scales 1 ≲ k/ Mpc^-1≲ 100, thereby considerably improving the constraint on power over these scales as compared to the bounds arrived at from CMB spectral distortion.

中文翻译：

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使用宇宙数据集约束超慢滚动膨胀


近年来，LIGO 和 PTA 合作探测到的引力波引发了小尺度物质能量过剩的有趣可能性。这种增加可以通过暴胀时期的超慢滚动（USR）阶段来实现。我们使用宇宙学数据集，特别是 CMB 各向异性和莱曼数据集，在此类模型的框架内限制小尺度上的过剩功率。 α 。我们根据 USR 开始时的 e-fold（从膨胀结束开始计算）N̅ ₁和 USR 阶段的持续时间 Δ N 来参数化 USR 阶段。前者决定了原始功率谱的增强规模，而后者决定了这种增强的幅度。从 CMB 和星系巡天的联合数据集中，我们获得 N̅ ₁ ≲ 45，且 Δ N 没有限制。这反过来意味着功率谱可以显着偏离典型慢滚的近尺度不变行为的尺度模型是k ≳1 Mpc ^-1 。另一方面，莱曼- α数据对沿视线的重子功率谱敏感。我们考虑半解析理论方法和高光谱分辨率莱曼- α数据来约束模型。 Lyman-α 数据限制了两个 USR 参数：N̅ ₁ ≲ 41 和 Δ N ≲ 0.4。这将功率谱增强的幅度限制为小于 1 ≲ k/ Mpc ^-1 ≲ 100 尺度上的一百倍，从而与从 CMB 频谱失真获得的界限相比，显着改善了这些尺度上对功率的约束。