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We calculate the conditions required to produce a large local trispectrum during two-field slow-roll inflation. This is done by extending and simplifying the 'heatmap' approach developed by Byrnes et al. The conditions required to generate…

Cosmology and Nongalactic Astrophysics · Physics 2014-03-10 Joseph Elliston , Laila Alabidi , Ian Huston , David J. Mulryne , Reza Tavakol

We study the non-Gaussianity generated during multiple-field inflation. We provide an exact expression for the bispectrum parameter f_NL which is valid beyond the slow-roll regime, valid for certain classes of inflationary models. We then…

Cosmology and Nongalactic Astrophysics · Physics 2011-11-04 Christian T. Byrnes , Gianmassimo Tasinato

In this paper we mainly focus on the curvature perturbation generated at the end of multi-field inflation, such as the multi-brid inflation. Since the curvature perturbation is produced on the super-horizon scale, the bispectrum and…

High Energy Physics - Theory · Physics 2010-04-15 Qing-Guo Huang

[Abridged] In contemporary literature, the calculation of modifications to the inflationary scalar power spectrum due to the loops from the higher order interaction terms in the Hamiltonian have led to a discussion regarding the validity of…

Cosmology and Nongalactic Astrophysics · Physics 2024-11-26 Suvashis Maity , H. V. Ragavendra , Shiv K. Sethi , L. Sriramkumar

We find constraints on inflationary dynamics that yield a large local bispectrum and/or trispectrum during two-field slow-roll inflation. This leads to simple relations between the non-Gaussianity parameters, simplifying the…

Cosmology and Nongalactic Astrophysics · Physics 2013-02-21 Joseph Elliston

We calculate the trispectrum of curvature perturbations for a model of inflation endowed with Galilean symmetry at the level of the fluctuations around an FRW background. Such a model has been shown to posses desirable properties such as…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 Nicola Bartolo , Emanuela Dimastrogiovanni , Matteo Fasiello

The trispectrum is at least as important as the bispectrum and its size can be characterized by two parameters $\tau_{NL}$ and $g_{NL}$. In this short paper, we focus on the Multi-brid inflation, in particular the two-brid inflation model…

High Energy Physics - Theory · Physics 2009-05-29 Qing-Guo Huang

We compute the leading order connected four-point function of the primordial curvature perturbation coming from the four-point function of the fields in multi-field DBI inflation models. We confirm that the consistency relations in the…

High Energy Physics - Theory · Physics 2009-10-29 Shuntaro Mizuno , Frederico Arroja , Kazuya Koyama

In this paper, we compute the inflationary trispectrum of primordial gauge fields generated through the scalar and tensor exchanges in models with spectator $U(1)$ gauge fields which are kinetically coupled to the inflaton. Focusing on the…

High Energy Physics - Theory · Physics 2025-09-16 P. Jishnu Sai , S. R. Haridev , Rajeev Kumar Jain

In models like axion monodromy, temporal features during inflation which are not associated with its ending can produce scalar, and to a lesser extent, tensor power spectra where deviations from scale-free power law spectra can be as large…

Cosmology and Nongalactic Astrophysics · Physics 2015-08-31 Hayato Motohashi , Wayne Hu

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

The nature of one-loop corrections to long-wavelength CMB-scale modes in single-field inflation models with an intermediate USR phase remains a subject of active debate. In this work, we perform a detailed investigation into the…

Cosmology and Nongalactic Astrophysics · Physics 2025-08-29 Haidar Sheikhahmadi , Amin Nassiri-Rad

We study the evolution of the non-linear curvature perturbation during perturbative reheating, and hence how observables evolve to their final values which we may compare against observations. Our study includes the evolution of the two…

Cosmology and Nongalactic Astrophysics · Physics 2013-08-23 Godfrey Leung , Ewan R. M. Tarrant , Christian T. Byrnes , Edmund J. Copeland

We calculate the squeezed limit of the bispectrum produced by inflation with multiple light fields. To achieve this we allow for different horizon exit times for each mode and calculate the intrinsic field-space three-point function in the…

Cosmology and Nongalactic Astrophysics · Physics 2016-04-07 Zachary Kenton , David J. Mulryne

We consider a class of multi-component hybrid inflation models whose evolution may be analytically solved under the slow-roll approximation. We call it multi-brid inflation (or $n$-brid inflation where $n$ stands for the number of inflaton…

Astrophysics · Physics 2009-10-09 Misao Sasaki

We evaluate the dimensionless non-Gaussianity parameter $h_{_{\rm NL}}$, that characterizes the amplitude of the tensor bispectrum, numerically for a class of two field inflationary models such as double inflation, hybrid inflation and…

Cosmology and Nongalactic Astrophysics · Physics 2017-07-26 Rathul Nath Raveendran , L. Sriramkumar

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 consider models of inflation that contain a transient non-slow-roll stage and investigate the conditions under which a dip appears in the power spectrum of the curvature perturbation. Using the $\delta N$ formalism, we derive a general…

Cosmology and Nongalactic Astrophysics · Physics 2025-09-19 Tomohiro Fujita , Ryodai Kawaguchi , Misao Sasaki , Yuichiro Tada

We develop an integral form for the bispectrum in general single-field inflation whose domain of validity includes models of inflation where the background evolution is not constrained to be slowly varying everywhere. Our integral form…

Cosmology and Nongalactic Astrophysics · Physics 2018-09-18 Peter Adshead , Wayne Hu , V Miranda

We compute the primordial trispectrum for curvature perturbations produced during cosmic inflation in models with standard kinetic terms, when the initial quantum state is not necessarily the vacuum state. The presence of initial…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 Ivan Agullo , Jose Navarro-Salas , Leonard Parker