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We investigate the non-Gaussian signatures of ultra slow-roll inflation. The bispectrum and the trispectrum are calculated with general initial conditions. The trispectrum is of local shape, as in the case of the bispectrum. We show that…

High Energy Physics - Theory · Physics 2015-06-15 Qing-Guo Huang , Yi Wang

A plateau on the background inflaton potential $V_{\rm b}(\phi)$ can lead cosmic inflation into an ultraslow-roll phase, greatly enhancing the primordial power spectrum on small scales, and resulting in intensive scalar-induced…

Cosmology and Nongalactic Astrophysics · Physics 2025-06-26 Shi-jie Wang , Nan Li

We construct models of inflation with many randomly interacting fields and use these to study the generation of cosmological observables. We model the potentials as multi-dimensional Gaussian random fields (GRFs) and identify powerful…

Cosmology and Nongalactic Astrophysics · Physics 2018-02-28 Theodor Bjorkmo , M. C. David Marsh

By assuming the spatially flat~FLRW line-element and employing the Hamiltonian formalism, a noncommutative (NC) setting of the Brans-Dicke (BD) theory is introduced. We investigate gravity-driven acceleration and kinetic inflation in this…

General Relativity and Quantum Cosmology · Physics 2017-01-18 S. M. M. Rasouli , Paulo Vargas Moniz

We investigate recent claims that brane inflation solves the overshoot problem through a combination of microphysical restrictions on the phase space of initial conditions and the existence of the Dirac-Born-Infeld (DBI) attractor in…

High Energy Physics - Theory · Physics 2009-09-02 Simeon Bird , Hiranya V. Peiris , Daniel Baumann

We present a two-field inflation model where inflaton field has a non-canonical kinetic term due to the presence of a dilaton field. It is a two-parameter generalization of one-parameter Brans-Dicke gravity in the Einstein frame. We show…

High Energy Physics - Phenomenology · Physics 2016-08-03 Girish Kumar Chakravarty , Suratna Das , Gaetano Lambiase , Subhendra Mohanty

Supersymmetric Unified theories which incorporate a renormalizable Type I seesaw mechanism for small neutrino masses can also provide slow roll inflection point inflation along a flat direction associated with a gauge invariant combination…

High Energy Physics - Phenomenology · Physics 2012-09-21 Charanjit S. Aulakh , Ila Garg

In this work we present several characteristic examples of theories of gravity and particle physics scenarios that may yield an observable energy spectrum of stochastic primordial gravitational waves, compatible with the 2023 NANOGrav…

Cosmology and Nongalactic Astrophysics · Physics 2023-08-01 V. K. Oikonomou

We derive the general formulae for the the scalar and tensor spectral tilts to the second order for the inflationary models with non-minimally derivative coupling without taking the high friction limit. The non-minimally kinetic coupling to…

General Relativity and Quantum Cosmology · Physics 2017-02-08 Nan Yang , Qin Fei , Qing Gao , Yungui Gong

The capability of Cosmic Inflation to explain the latest Cosmic Microwave Background and Baryonic Acoustic Oscillation data is assessed by performing Bayesian model comparison within the landscape of nearly three-hundred models of…

Cosmology and Nongalactic Astrophysics · Physics 2024-08-27 Jerome Martin , Christophe Ringeval , Vincent Vennin

Inflationary $\alpha$-attractor models in supergravity, which provide excellent fits to the latest observational data, are based on the Poincare disk hyperbolic geometry. We refine these models by constructing Kahler potentials with…

High Energy Physics - Theory · Physics 2015-09-23 John Joseph M. Carrasco , Renata Kallosh , Andrei Linde

It is investigated the reconstruction during the slow-roll inflation in the most general class of scalar-torsion theories whose Lagrangian density is an arbitrary function $f(T,\phi)$ of the torsion scalar $T$ of teleparallel gravity and…

General Relativity and Quantum Cosmology · Physics 2021-08-17 Manuel Gonzalez-Espinoza , Ramón Herrera , Giovanni Otalora , Joel Saavedra

Inflationary models with a non-zero background curvature require additional hypothesis or parameters compared to flat inflation and the procedure to construct them cannot be as simple as in the flat case. For this reason, there is no…

General Relativity and Quantum Cosmology · Physics 2024-11-04 Quentin Vigneron , Julien Larena

We investigate the influence on the inflationary predictions from the reheating processes characterized by the $e$-folding number $N_{\mathrm{reh}}$ and the effective equation-of-state parameter $w_{\mathrm{reh}}$ during the reheating…

General Relativity and Quantum Cosmology · Physics 2015-09-10 Rong-Gen Cai , Zong-Kuan Guo , Shao-Jiang Wang

In single-field, slow-roll inflationary models, scalar and tensorial (Gaussian) perturbations are both characterized by a zero mean and a non-zero variance. In position space, the corresponding variance of those fields diverges in the…

General Relativity and Quantum Cosmology · Physics 2014-11-20 I. Agullo , J. Navarro-Salas , Gonzalo J. Olmo , Leonard Parker

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

It has been pointed out that a large non-minimal coupling $\xi$ between the Higgs and the Ricci scalar can source higher derivative operators, which may change the predictions of Higgs inflation. A variant, called critical Higgs inflation,…

High Energy Physics - Phenomenology · Physics 2018-04-03 Alberto Salvio

We update predictions for observables in the "delicate" D3/anti-D3 inflationary model on the conifold. We use a full CMB likelihood calculation to assess goodness-of-fit, which is necessary because in this model the zeta power spectrum…

Cosmology and Nongalactic Astrophysics · Physics 2022-02-11 Kareem Marzouk , Alessandro Maraio , David Seery

Loop corrections to primordial correlation functions are unavoidable due to the non-linear nature of gravity. Previous works have established a robust framework for computing the renormalised one-loop power spectra of scalar and tensor…

Cosmology and Nongalactic Astrophysics · Physics 2026-03-13 Matteo Braglia , Sebastián Céspedes , Lucas Pinol

Based on the dynamics of single scalar field slow-roll inflation and the theory of reheating, we investigate the generalized natural inflationary (GNI) model. Concretely, we give constraints on the scalar spectral index $n_{s}$ and…

Cosmology and Nongalactic Astrophysics · Physics 2020-07-02 Nan Zhang , Ya-Bo Wu , Jun-Wang Lu , Chu-Wen Sun , Li-Jie Shou , Hai-Zhou Xu