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We calculate power spectra of cosmological perturbations at high accuracy for two classes of inflation models. We classify the models according to the behaviour of the Hubble distance during inflation. Our approximation works if the Hubble…

Astrophysics · Physics 2009-11-06 Dominik J. Schwarz , Cesar A. Terrero-Escalante , Alberto A. Garcia

If a coupling between the inflaton and the Gauss-Bonnet term is introduced, many models of inflation that were ruled out by the most recent Planck data can be made viable again. The predictions for the scalar spectral index and…

General Relativity and Quantum Cosmology · Physics 2025-04-22 Kamil Mudrunka , Kazunori Nakayama

In this work, I consider an inflation model with a quadratic potential and a negative cosmological constant. An analytical solution of the equation of motion for the inflaton field is found without slow-roll approximation. The result is…

High Energy Physics - Phenomenology · Physics 2023-04-19 Chia-Min Lin

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 analyze the impact of breaking diffeomorphism invariance in the inflaton sector. In particular, we consider inflaton models which are invariant under the subgroup of transverse diffeomorphisms and address the possibility of implementing…

General Relativity and Quantum Cosmology · Physics 2026-04-13 Antonio L. Maroto , Prado Martín-Moruno , Miguel Orbaneja-Pérez

We study slow-roll inflation as a common feature in Metric-affine Theories of Gravity. In particular, we take into account extended metric, teleparallel and symmetric-teleparallel theories of gravity, based on different geometric…

General Relativity and Quantum Cosmology · Physics 2024-09-02 Salvatore Capozziello , Mehdi Shokri

Nonminimal coupling of the inflaton field to the Ricci curvature of spacetime is generally unavoidable, and the paradigm of inflation should be generalized by including the corresponding term in the Lagrangian of the inflationary theory.…

High Energy Physics - Theory · Physics 2014-11-18 Valerio Faraoni

We study the dual 3d Euclidean RG flow of single-field slow-roll Inflation using the postulates of the dS/CFT correspondence. For that purpose we solve for the inflationary fluctuation at all times using a matching procedure between two…

High Energy Physics - Theory · Physics 2015-06-17 Uri Kol

In negatively curved field spaces, inflation can be realised even in steep potentials. Hyperinflation invokes the `centrifugal force' of a field orbiting the hyperbolic plane to sustain inflation. We generalise hyperinflation by showing…

High Energy Physics - Theory · Physics 2019-05-22 Theodor Bjorkmo , M. C. David Marsh

We investigate slow-roll inflation within the framework of Kaniadakis and dual Kaniadakis cosmology, where the usual entropy formalism is generalized through a deformation parameter $\kappa$. By deriving the modified Friedmann equations and…

General Relativity and Quantum Cosmology · Physics 2026-05-19 Leila Liravi , Ahmad Sheykhi

We compare the standard single scalar field inflationary predictions with those of an inflationary phase driven by a tachyon field. A slow-roll formalism is defined for tachyon inflation, and we derive the spectra of scalar and tensor…

High Energy Physics - Theory · Physics 2008-11-26 D. A. Steer , F. Vernizzi

We describe how to apply the transport method to compute inflationary observables in a broad range of multiple-field models. The method is efficient and encompasses scenarios with curved field-space metrics, violations of slow-roll…

Cosmology and Nongalactic Astrophysics · Physics 2016-01-20 Mafalda Dias , Jonathan Frazer , David Seery

We investigate all single-field, slow-roll inflationary models whose slow-roll parameters scale as 1/N in the limit of a large number of e-folds N. We proof that all such models belong to two universality classes, characterised by a single…

High Energy Physics - Theory · Physics 2015-06-17 Diederik Roest

We study the inflationary dynamics in a model of slow-roll inflation in warped throat. Inflation is realized by the motion of a D-brane along the radial direction of the throat, and at later stages instabilities develop in the angular…

High Energy Physics - Theory · Physics 2010-11-30 Heng-Yu Chen , Jinn-Ouk Gong , Kazuya Koyama , Gianmassimo Tasinato

The primordial power spectra of scalar and tensor perturbations during slow-roll inflation are usually calculated with the method of Bessel function approximation. For constant-roll or ultra slow-roll inflation, the method of Bessel…

General Relativity and Quantum Cosmology · Physics 2018-04-09 Zhu Yi , Yungui Gong

We propose new classes of inflation models based on the modular symmetry, where the modulus field $\tau$ serves as the inflaton. We establish a connection between modular inflation and modular stabilization, wherein the modulus field rolls…

High Energy Physics - Phenomenology · Physics 2024-10-21 Gui-Jun Ding , Si-Yi Jiang , Wenbin Zhao

A unified approach to quintessence and inflation is investigated with the use of a single scalar field. It is argued that successful potentials have to approximate a combination of exponential and inverse power-law decline in the limit of…

Astrophysics · Physics 2007-05-23 Konstantinos Dimopoulos

Using the constant-roll approach, DBI inflationary scenario will be studied and it is sought to compare the result with observational data. By considering the cosmological perturbations of the model, it is realized that some extra terms…

General Relativity and Quantum Cosmology · Physics 2020-05-12 Abolhassan Mohammadi , Tayeb Golanbari , Khaled Saaidi

By applying a particular kind of modified gravity, we study the inflation. Precisely, we extend our investigations beyond the Einstein's gravity to explore the Natural inflation model via the term $F(\phi)T$. We compute the inflation…

General Relativity and Quantum Cosmology · Physics 2025-07-30 Feyzollah Younesizadeh , Davoud Kamani

We derive consistency conditions for sustained slow roll and rapid turn inflation in two-field cosmological models with oriented scalar field space, which imply that inflationary models with field-space trajectories of this type are…

High Energy Physics - Theory · Physics 2023-05-18 Lilia Anguelova , Calin Iuliu Lazaroiu