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In addition to generating the appropriate perturbation power spectrum, an inflationary scenario must take into account the need for inflation to end subsequently. In the context of single-field inflation models where inflation ends by…

天体物理学 · 物理学 2009-11-10 Michaël Malquarti , Samuel M. Leach , Andrew R. Liddle

Large turns in multifield inflation can lead to a very rich phenomenology, but are difficult to realise in supergravity, and typically require large field space curvatures. In this work, we present a mechanism to realise multiple sharp…

宇宙学与河外天体物理 · 物理学 2023-05-24 Sukannya Bhattacharya , Ivonne Zavala

The early dark energy resolution of Hubble tension seems to be suggesting a scale-invariant Harrison-Zeldovich spectrum of primordial scalar perturbation, i.e. $n_s=1$ ($|n_s-1|\sim {\cal O}(0.001)$) for $H_0\sim 73$km/s/Mpc. In this work,…

宇宙学与河外天体物理 · 物理学 2026-04-06 Hao-Shi Yuan , Ze-Yu Peng , Yun-Song Piao

During slow-roll inflation, non-perturbative transitions can produce bubbles of metastable vacuum. These bubbles expand exponentially during inflation to super-horizon size, and later collapse into black holes when the expansion of the…

高能物理 - 理论 · 物理学 2023-11-21 Matthew Kleban , Cameron E. Norton

By a careful implementation of gauge transformations involving long-wavelength modes, we show that a variety of effects involving squeezed bispectrum configurations, for which one Fourier mode is much shorter than the other two, cannot be…

宇宙学与河外天体物理 · 物理学 2021-02-03 Sabino Matarrese , Luigi Pilo , Rocco Rollo

We investigate the accuracy of slow-roll inflation in light of current observational constraints, which do not allow for a large deviation from scale invariance. We investigate the applicability of the first and second order slow-roll…

天体物理学 · 物理学 2007-05-23 Alexey Makarov

An estimate of the one-loop correction to the power spectrum of the primordial curvature perturbation is given, assuming it is generated during a phase of single-field, slow-roll inflation. The loop correction splits into two parts, which…

天体物理学 · 物理学 2010-02-09 David Seery

If we posit the validity of the consistency relations, the tensor spectral index and the relative amplitude of the scalar and tensor power spectra are both fixed by a single slow roll parameter. The physics of the protoinflationary…

高能物理 - 理论 · 物理学 2015-06-19 Massimo Giovannini

During inflation, vacuum quantum fluctuations are amplified and stretched to astrophysical distances. They give rise to fluctuations in the cosmic microwave background (CMB) temperature and polarisation, and to large-scale structures in our…

宇宙学与河外天体物理 · 物理学 2022-03-03 Vincent Vennin

Inflation provides a suitable environment for the formation of Primordial Black Holes(PBHs). In this article, we examine the formation of primordial black holes in the Mutated Hilltop inflation model coupled with the Einstein-Gauss-Bonnet…

广义相对论与量子宇宙学 · 物理学 2025-01-06 Yogesh , Abolhassan Mohammadi

In this paper we use two methods to constrain the the canonical single-field slow-roll inflation model. The first method exploits the analytic slow-roll-parameter dependence of primordial perturbations, and the second consists of a…

宇宙学与河外天体物理 · 物理学 2025-11-17 Jun Li , Guang-Hai Guo

We investigate the one-loop quantum correction to the power spectrum of primordial curvature perturbations in the ultra-slow-roll (USR) inflationary scenario, incorporating the backreaction effect from curvature perturbations. In the…

广义相对论与量子宇宙学 · 物理学 2025-07-30 Cheng-Jun Fang , Zhen-Hong Lyu , Chao Chen , Zong-Kuan Guo

We study a model of two-field ultra-slow-roll (USR) inflation bounded by a curve in the field space. Curvature perturbations and non-Gaussianities can be enhanced both during the USR phase and from the inhomogeneities at the boundary. We…

宇宙学与河外天体物理 · 物理学 2022-09-05 Sina Hooshangi , Alireza Talebian , Mohammad Hossein Namjoo , Hassan Firouzjahi

We study multiple fields inflation in diffusion dominated regime using stochastic $\delta N$ formalism. The fields are under pure Brownian motion in a dS background with boundaries in higher dimensional field space. This setup can be…

宇宙学与河外天体物理 · 物理学 2023-04-04 Kosar Asadi , Amin Nassiri-Rad , Hassan Firouzjahi

Constant-roll inflation was recently introduced by Motohashi, Starobinsky and Yokoyama as a phenomenological way to parametrize deviations from the slow-roll scenarios. In this paper, we investigate the dynamics of both the background and…

宇宙学与河外天体物理 · 物理学 2019-05-29 Jose T. Galvez Ghersi , Alex Zucca , Andrei V. Frolov

We study multifield contributions to the scalar power spectrum in an ensemble of six-field inflationary models obtained in string theory. We identify examples in which inflation occurs by chance, near an approximate inflection point, and we…

宇宙学与河外天体物理 · 物理学 2015-06-05 Liam McAllister , Sébastien Renaux-Petel , Gang Xu

We examine the regime of validity of $N$-point spectra predictions of single field inflation models that invoke transient periods of non-adiabatic evolution. Such models generate oscillatory features in these spectra spanning frequencies up…

宇宙学与河外天体物理 · 物理学 2014-04-30 Peter Adshead , Wayne Hu

We examine single-field inflationary models for the formation of primordial black holes (PBHs). By analyzing the latest observations from the Atacama Cosmology Telescope (ACT)~\cite{ACT:2025fju, ACT:2025tim}, we demonstrate that the…

宇宙学与河外天体物理 · 物理学 2026-02-24 Sasha Allegrini , Antonio J. Iovino , Hardi Veermäe

Stochastic inflation resolves primordial perturbations non-linearly, probing their probability distribution deep into its non-Gaussian tail. The strongest perturbations collapse into primordial black holes. In typical black-hole-producing…

宇宙学与河外天体物理 · 物理学 2023-08-07 Eemeli Tomberg

We point out the existing confusions about the slowroll parameters and conditions for multifield inflation. If one requires the fields to roll down the gradient flow, we find that only articles adopting the Hubble slowroll expansion are on…

高能物理 - 理论 · 物理学 2013-05-30 I-Sheng Yang