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In this work, we systematically investigate the inflationary complexity of the two-mode squeezed state with thermal effect for the single field inflation, modified dispersion relation, and non-trivial sound speed with the method of closed…

High Energy Physics - Theory · Physics 2024-05-07 Tao Li , Lei-Hua Liu

Previous work on the gravitational-wave background generated in a two-scalar-field cosmological model, in which warm inflation and the dark sector are unified within a single framework, has shown that the resulting spectrum could be…

General Relativity and Quantum Cosmology · Physics 2026-04-23 Orlando Luongo , Tommaso Mengoni , Paulo M. Sá

We develop a variant of the generalized slow roll approach for calculating the curvature power spectrum that is well-suited for order unity deviations in power caused by sharp features in the inflaton potential. As an example, we show that…

Cosmology and Nongalactic Astrophysics · Physics 2010-07-07 Cora Dvorkin , Wayne Hu

We present a new method to calculate the spectrum of (slow-roll) inflationary perturbations, inspired by the conjectured dS/CFT correspondence. We show how the standard result for the spectrum of inflationary perturbations can be obtained…

High Energy Physics - Theory · Physics 2014-11-18 Jan Pieter van der Schaar

Inflation, a period of exponential expansion in the early Universe, is considered an important part of the standard $\Lambda$CDM cosmological model, and plays a crucial role in explaining a wide range of current observations. The standard…

General Relativity and Quantum Cosmology · Physics 2023-12-08 Maria Pia Piccirilli , Gabriel Leon

We show that the characteristic function of the probability distribution associated with the change of an observable in a two-point measurement protocol with a perturbation can be written as an auto-correlation function between an initial…

Quantum Physics · Physics 2023-11-15 Ankit Gill , Kunal Pal , Kuntal Pal , Tapobrata Sarkar

We investigate the generation of gravitational waves in the hybrid quintessential inflationary model. The full gravitational-wave energy spectrum is calculated using the method of continuous Bogoliubov coefficients. The post-inflationary…

General Relativity and Quantum Cosmology · Physics 2015-03-13 Paulo M. Sá , Alfredo B. Henriques

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

The BB-mode angular correlation power spectrum of CMB is obtained by considering the primordial gravitational waves in the squeezed vacuum state for various inflationary models and results are compared with the joint analysis of the…

Cosmology and Nongalactic Astrophysics · Physics 2016-05-25 N. Malsawmtluangi , P. K. Suresh

We introduce a new implementation of time-dependent density-functional theory which allows the \emph{entire} spectrum of a molecule or extended system to be computed with a numerical effort comparable to that of a \emph{single} standard…

Materials Science · Physics 2009-11-13 Dario Rocca , Ralph Gebauer , Yousef Saad , Stefano Baroni

We give a new interpretation of the effect of initial state entanglement on the spectrum of vacuum fluctuations. We consider an initially entangled state between two free massive scalar fields in de Sitter space. We construct the initial…

High Energy Physics - Theory · Physics 2016-12-30 Sugumi Kanno

The quantum-to-classical transition of inflationary perturbations remains an unresolved fundamental problem, and quantum decoherence is one of the promising solutions. By considering quantum perturbations during inflation as an open quantum…

General Relativity and Quantum Cosmology · Physics 2025-07-01 Zhongkai Wang , Yungui Gong

In the inflationary cosmology it occurs frequently that the inflaton field is trapped in a local, transient minimum with non-zero vacuum energy. The difficulty regarding the curvature perturbation produced during such a stage is that…

Astrophysics · Physics 2009-06-23 Jinn-Ouk Gong , Misao Sasaki

We explore the consequences of loop quantum cosmology (inverse-volume corrections) in the spectrum of the gravitational waves using the method of the Bogoliubov coefficients. These corrections are taken into account at the background level…

General Relativity and Quantum Cosmology · Physics 2014-01-22 Joao Morais , Mariam Bouhmadi-Lopez , Alfredo B. Henriques

We study the two-field warm inflation models with a double quadratic potential and a linear temperature dependent dissipative coefficient. We derived the evolution equation of all kinds of perturbations without assuming slow-roll…

General Relativity and Quantum Cosmology · Physics 2019-05-23 Yang-yang Wang , Xiao-Min Zhang , Jian-Yang Zhu

In this work we present an inflationary mechanism based on fluid dynamics. Starting with the action for a single barotropic perfect fluid, we outline the procedure to calculate the power spectrum and the bispectrum of the curvature…

High Energy Physics - Theory · Physics 2015-06-16 Xingang Chen , Hassan Firouzjahi , Mohammad Hossein Namjoo , Misao Sasaki

We derive the power spectrum $\mathcal P(k)$ of the density perturbations produced during inflation up to second-order corrections in the standard slow-roll approximation for an inflaton with more than one degree of freedom. We also present…

Astrophysics · Physics 2008-11-26 Jin-Ook Gong , Ewan D. Stewart

The evolutions of the flat FLRW universe and its linear perturbations are studied systematically in the dressed metric approach of LQC. When it is dominated by the kinetic energy of the inflaton at the quantum bounce, the evolution of the…

General Relativity and Quantum Cosmology · Physics 2017-10-25 Tao Zhu , Anzhong Wang , Gerald Cleaver , Klaus Kirsten , Qin Sheng

We show that a scalar excited state with large occupation numbers during inflation leads to an enhancement of tensor modes and a characteristic pattern of order-one oscillations in the associated stochastic gravitational wave background…

Cosmology and Nongalactic Astrophysics · Physics 2022-04-07 Jacopo Fumagalli , Gonzalo A. Palma , Sébastien Renaux-Petel , Spyros Sypsas , Lukas T. Witkowski , Cristobal Zenteno

The theory of inflation provides a mechanism to explain the structures we observe today in the Universe, starting from quantum-mechanically generated fluctuations. However, this leaves the question of: how did the quantum-to-classical…

Cosmology and Nongalactic Astrophysics · Physics 2024-12-16 Jessie de Kruijf , Nicola Bartolo