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We construct explicit models of multi-field inflation in which the primordial metric fluctuations do not necessarily obey Gaussian statistics. These models are realizations of mechanisms in which non-Gaussianity is first generated by a…

Astrophysics · Physics 2008-11-26 Francis Bernardeau , Jean-Philippe Uzan

In this article, we study in detail the linear dynamics and cubic interactions for any number $N_\mathrm{field}$ of scalar fields during inflation, directly in terms of the observable curvature perturbation $\zeta$ and $N_\mathrm{field}-1$…

Cosmology and Nongalactic Astrophysics · Physics 2021-05-11 Lucas Pinol

We discuss how primordial non-Gaussianity of the curvature perturbation helps to constrain models of the early universe. Observations are consistent with Gaussian initial conditions, compatible with the predictions of the simplest models of…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-26 Christian T. Byrnes

In hybrid inflationary models, inflation ends by a sudden instability associated with a steep ridge in the potential. Here we argue that this feature can generate a large contribution to the curvature perturbation on observable scales. This…

Cosmology and Nongalactic Astrophysics · Physics 2010-02-21 David Mulryne , David Seery , Daniel Wesley

If cosmic inflation suffered tiny time-dependent deviations from the slow-roll regime, these would induce the existence of small scale-dependent features imprinted in the primordial spectra, with their shapes and sizes revealing information…

Cosmology and Nongalactic Astrophysics · Physics 2016-09-21 Sander Mooij , Gonzalo A. Palma , Grigoris Panotopoulos , Alex Soto

The statistics of multi-field inflation are investigated using the stochastic approach. We analytically obtain the probability distribution function of fields with the scaling approximation by extending the previous work by Amendola. The…

Astrophysics · Physics 2009-11-11 Takeshi Hattori , Kazuhiro Yamamoto

We use holographic techniques to compute inflationary non-Gaussianities for general single-field inflation, including models with a non-trivial sound speed. In this holographic approach, the inflationary dynamics is captured by a relevant…

High Energy Physics - Theory · Physics 2016-12-14 Hiroshi Isono , Toshifumi Noumi , Gary Shiu , Sam S. C. Wong , Siyi Zhou

We study Dirac-Born-Infeld (DBI) inflation models with multiple scalar fields. We show that the adiabatic and entropy modes propagate with a common effective sound speed and are thus amplified at the sound horizon crossing. In the small…

High Energy Physics - Theory · Physics 2008-11-26 David Langlois , Sebastien Renaux-Petel , Daniele A. Steer , Takahiro Tanaka

We calculate the general solutions for a warm inflationary scenario with weak dissipation, reviewing the dissipative dynamics of the two-fluid system, and calculate the bispectrum of the gravitational field fluctuations generated in the…

Astrophysics · Physics 2008-11-26 Sujata Gupta

Recently multi-field inflation models that can produce large scalar fluctuations on small scales have drawn a lot of attention, primarily because they could lead to primordial black hole production and generation of large second-order…

Cosmology and Nongalactic Astrophysics · Physics 2023-09-21 Laura Iacconi , David J. Mulryne

We conduct a thorough study of the comoving curvature perturbation $\mathcal{R}$ in single-field inflation with two stages, represented by a piecewise quadratic potential, where both the first and second derivatives are allowed to be…

Cosmology and Nongalactic Astrophysics · Physics 2025-06-23 Xinpeng Wang , Xiao-Han Ma , Misao Sasaki

Inflationary model driven by a scalar field whose potential has a step in the second derivative with respect to the field is considered. For the best fit potential parameter values, the 3-point function and the non-Gaussianity associated…

Cosmology and Nongalactic Astrophysics · Physics 2023-04-11 Rakhi. R , Minu Joy

Single field inflationary models predict nearly Gaussian initial conditions and hence a detection of non-Gaussianity would be a signature of the more complex inflationary scenarios. In this paper we study the effect on the cosmic microwave…

Cosmology and Nongalactic Astrophysics · Physics 2010-11-02 Dmitriy Tseliakhovich , Christopher Hirata , Anze Slosar

The physics of primordial black holes can be affected by the non-Gaussian statistics of the density fluctuations that generate them. Therefore, it is important to have good theoretical control of the higher-order correlation functions for…

High Energy Physics - Theory · Physics 2024-04-16 Gianmassimo Tasinato

We study the bispectrum of the curvature perturbation on uniform energy density hypersurfaces in models of inflation with two scalar fields evolving simultaneously. In the case of a separable potential, it is possible to compute the…

Astrophysics · Physics 2009-11-11 Filippo Vernizzi , David Wands

We develop analytic and numerical techniques for studying the statistics of slow-roll inflation in random Gaussian landscapes. As an illustration of these techniques, we analyze small-field inflation in a one-dimensional landscape. We…

High Energy Physics - Theory · Physics 2017-06-14 Ali Masoumi , Alexander Vilenkin , Masaki Yamada

We present a new efficient method for computing the non-linearity parameters of the higher order correlation functions of local type curvature perturbations in inflation models having a $\cal N$-component scalar field, focusing on the…

Astrophysics · Physics 2014-11-18 Shuichiro Yokoyama , Teruaki Suyama , Takahiro Tanaka

We compute the three point correlation functions for primordial scalar and tensor fluctuations in single field inflationary models. We obtain explicit expressions in the slow roll limit where the answer is given terms of the two usual slow…

Astrophysics · Physics 2009-11-07 Juan Maldacena

We show that a conformal-invariance violating coupling of the inflaton to electromagnetism produces a cross correlation between curvature fluctuations and a spectrum of primordial magnetic fields. According to this model, in the case of…

Cosmology and Nongalactic Astrophysics · Physics 2013-05-30 Leonardo Motta , Robert R. Caldwell

We present the model-independent studies of non attractor inflation in the context of effective field theory (EFT) of inflation. Within the EFT approach two independent branches of non-attractor inflation solutions are discovered in which a…

High Energy Physics - Theory · Physics 2015-08-06 Mohammad Akhshik , Hassan Firouzjahi , Sadra Jazayeri