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We investigate the consistency relation relating the squeezed limit of the bispectrum to the scalar spectral index in single field models of inflation. We give a simple integral formula for the bispectrum in the squeezed limit in terms of…

Cosmology and Nongalactic Astrophysics · Physics 2011-01-27 Sébastien Renaux-Petel

Features in the primordial power spectrum require numerical methods that are both accurate and scalable across the wide class of multifield inflationary models that produce them. Sharp turns in the background trajectories, induced by either…

General Relativity and Quantum Cosmology · Physics 2026-03-31 Guillermo F. Quispe Peña , Johor D. Peñalba Quispitupa , José T. Gálvez Ghersi

We study constant roll inflation systematically. This is a regime, in which the slow roll approximation can be violated. It has long been thought that this approximation is necessary for agreement with observations. However, recently it was…

High Energy Physics - Theory · Physics 2018-02-21 Lilia Anguelova , Peter Suranyi , L. C. Rohana Wijewardhana

We consider inflation using a class of non-canonical Lagrangians for which the modification to the kinetic term depends on the field, but not its derivatives. We generalize the standard Hubble slow roll expansion to the non-canonical case…

Astrophysics · Physics 2010-10-27 Gabriela Barenboim , William H. Kinney

The delta N formula that relates the final curvature perturbation on comoving slices to the inflaton perturbation on flat slices after horizon crossing is a powerful and intuitive tool to compute the curvature perturbation spectrum from…

Astrophysics · Physics 2009-10-09 Hyun-Chul Lee , Misao Sasaki , Ewan D. Stewart , Takahiro Tanaka , Shuichiro Yokoyama

Slow-roll of the inflaton (inflationary field) defines the standard dynamics of the inflationary epoch. However, the inflaton deviates from slow-roll when it encounters an extremely flat region in the inflationary potential, and enters a…

General Relativity and Quantum Cosmology · Physics 2025-10-28 Aarav Shah

We study the general relation between the power spectrum and the squeezed limit of the bispectrum of the comoving curvature perturbation produced during single-field slow-roll inflation when the initial state is a general vacuum. Assuming…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 Jinn-Ouk Gong , Misao Sasaki

We propose a single field inflationary model by generalizing the inverse power law potential from the intermediate model. We study the implication of our model on the primordial anisotropy of cosmological microwave background radiation.…

High Energy Physics - Theory · Physics 2015-06-17 Zhun Lu

Nongaussian statistics are a powerful discriminant between inflationary models, particularly those with noncanonical kinetic terms. Focusing on theories where the Lagrangian is an arbitrary Lorentz-invariant function of a scalar field and…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-19 Clare Burrage , Raquel H. Ribeiro , David Seery

We present a detailed study of the trispectrum of the curvature perturbation generated within a stable, well defined and predictive theory which comprises an inflationary phase. In this model the usual shift symmetry is enhanced up to the…

Cosmology and Nongalactic Astrophysics · Physics 2016-04-18 Frederico Arroja , Nicola Bartolo , Emanuela Dimastrogiovanni , Matteo Fasiello

We develop a frame-covariant formulation of inflation in the slow-roll approximation by generalizing the inflationary attractor solution for scalar-curvature theories. Our formulation gives rise to new generalized forms for the potential…

High Energy Physics - Phenomenology · Physics 2016-06-22 Daniel Burns , Sotirios Karamitsos , Apostolos Pilaftsis

We implement Slow Roll Reconstruction -- an optimal solution to the inverse problem for inflationary cosmology -- within ModeCode, a publicly available solver for the inflationary dynamics. We obtain up-to-date constraints on the…

Cosmology and Nongalactic Astrophysics · Physics 2012-07-10 Jorge Noreña , Christian Wagner , Licia Verde , Hiranya V. Peiris , Richard Easther

We analyse the post-inflationary contribution to the stochastic gravitational wave background due to a resonant feature in the scalar power spectrum, which is characterised by an oscillation in $\log(k)$, complementing our previous work…

Cosmology and Nongalactic Astrophysics · Physics 2021-09-08 Jacopo Fumagalli , Sébastien Renaux-Petel , Lukas T. Witkowski

Non-linear interactions during inflation generate non-Gaussianities in the distribution of primordial curvature. In many theories, the physics is scale-invariant, such that the induced three-point function depends solely on a dimensionless…

Cosmology and Nongalactic Astrophysics · Physics 2026-03-27 Oliver H. E. Philcox

We consider Einstein-Gauss-Bonnet (EGB) inflationary models using the effective potential approach. We present evolution equations in the slow-roll regime using the effective potential and the tensor-to-scalar ratio. The choice of the…

General Relativity and Quantum Cosmology · Physics 2021-06-30 Ekaterina O. Pozdeeva

In view of cosmological parameters being measured to ever higher precision, theoretical predictions must also be computed to an equally high level of precision. In this work we investigate the impact on such predictions of relaxing some of…

Cosmology and Nongalactic Astrophysics · Physics 2018-05-23 Mindaugas Karčiauskas , Kazunori Kohri , Taro Mori , Jonathan White

A perturbative strategy for inflation described by two-inflaton fields is developed using a mathematical analogy with the renormalization-group. Two small quantities, $\alpha$ and $\lambda$, corresponding to standard slow-roll parameters…

High Energy Physics - Theory · Physics 2025-06-10 Bohdan Grzadkowski , Marco Piva

We explore some issues in slow roll inflation in situations where field excursions are small compared to $M_p$. We argue that for small field inflation, minimizing fine tuning requires low energy supersymmetry and a tightly constrained…

High Energy Physics - Phenomenology · Physics 2015-05-30 Michael Dine , Lawrence Pack

We revisit the Cosmic Microwave Background (CMB) constraints on the spatial curvature of the Universe, assessing how they change when the curvature parameter and the primordial inflationary scalar spectrum are treated consistently within…

Cosmology and Nongalactic Astrophysics · Physics 2025-10-01 Enrico Specogna , Tatevik Vardanyan , William Giarè , Eleonora Di Valentino

In non-attractor single-field inflation models producing a scale-invariant power spectrum, the curvature perturbation on super-horizon scales grows as ${\cal R}\propto a^3$. This is so far the only known class of self-consistent…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-17 Xingang Chen , Hassan Firouzjahi , Eiichiro Komatsu , Mohammad Hossein Namjoo , Misao Sasaki