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We revisit the scenario where inflation is preceded by a radiation era by considering that the inflaton too could have been in thermal equilibrium early in the radiation era. Hence we take into account not only the effect of a…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 Suratna Das , Gaurav Goswami , Jayanti Prasad , Raghavan Rangarajan

The possibility of the resilience of the beginning of inflation under unfavorable conditions is examined by considering the initial state of the inflaton field to be in the form of a relativistic gas with some of its properties in close…

High Energy Physics - Theory · Physics 2023-04-05 Lasha Berezhiani , Mark Trodden

A formula for the power spectrum of curvature perturbations having any initial conditions in inflation is obtained. Based on the physical conditions before inflation, the possibility exists that the initial state of scalar perturbations is…

High Energy Physics - Theory · Physics 2017-08-23 Shiro Hirai

In this work we shall consider the effects of a geometrically generated post-inflationary era on the energy spectrum of the primordial gravitational waves. Specifically, we shall consider a post-inflationary constant equation of state era,…

General Relativity and Quantum Cosmology · Physics 2022-09-13 V. K. Oikonomou

How sensitive are the predictions of inflation to pre-inflationary conditions when the number of efolds of inflation is not too large? In an attempt to address this question, we consider a simple model where the inflationary era is preceded…

High Energy Physics - Theory · Physics 2016-01-27 Sina Bahrami , Eanna E. Flanagan

We explore the possibility of a single field quasi-de Sitter inflationary model with general initial state for primordial fluctuations. In this paper, first we compute the power spectrum and the bispectrum of scalar perturbations with…

Cosmology and Nongalactic Astrophysics · Physics 2012-03-02 Sandipan Kundu

In this paper we skim the true phenomenological requirements behind the concept of inflationary squeezing. We argue that all that is required is that at horizon re-entry the fluctuations form standing waves with the correct temporal phase…

General Relativity and Quantum Cosmology · Physics 2017-11-15 Giulia Gubitosi , Joao Magueijo

We investigate the dependence of the gravitational wave spectrum from quintessential inflation on the reheating process. We consider two extreme reheating processes. One is the gravitational reheating by particle creation in the expanding…

General Relativity and Quantum Cosmology · Physics 2009-10-09 Hiroyuki Tashiro , Takeshi Chiba , Misao Sasaki

If the initial state of the inflaton field is taken to have a thermal distribution instead of the conventional zero particle vacuum state then the curvature power spectrum gets modified by a temperature dependent factor such that the…

High Energy Physics - Phenomenology · Physics 2008-11-26 Kaushik Bhattacharya , Subhendra Mohanty , Raghavan Rangarajan

The initial condition problem of inflation is examined from the perspective of both spacetime embedding and scalar field dynamics. The spacetime embedding problem is solved for arbitrary initial spatial curvature Omega, which generalizes…

High Energy Physics - Phenomenology · Physics 2009-10-31 Arjun Berera , Christopher Gordon

Starting from an initial state of thermal equilibrium, we derive an expression for the quantum fluctuation in the energy density during the inflationary epoch in terms of the mode functions for the inflaton field. The effect of this…

High Energy Physics - Phenomenology · Physics 2009-10-31 Amit Kundu , S. Mallik , D. Rai Chaudhuri

In this work we examine the effects of a pre-inflationary de Sitter bounce on the energy spectrum of the primordial gravitational waves. Specifically we assume that the Universe is described by several evolution patches, starting with a de…

General Relativity and Quantum Cosmology · Physics 2022-10-19 V. K. Oikonomou

Supersolid inflation is a class of inflationary theories that simultaneously breaks time and space reparameterization invariance during inflation, with distinctive features for the dynamics of cosmological fluctuations. We investigate…

Cosmology and Nongalactic Astrophysics · Physics 2017-07-19 Angelo Ricciardone , Gianmassimo Tasinato

Primordial gravitational waves generated during inflation lead to the B-mode polarization in the cosmic microwave background and a stochastic gravitational wave background in the Universe. We will explore the current constraint on the tilt…

Cosmology and Nongalactic Astrophysics · Physics 2025-03-28 Jun Li , Zu-Cheng Chen , Qing-Guo Huang

We investigate the properties of gravitational waves generated by heating induced phase transitions in warm inflation. In this scenario, the heating phase of inflation followed by subsequent cosmological cooling can trigger two associated…

General Relativity and Quantum Cosmology · Physics 2025-10-28 Xiao-Bin Sui , Jing Liu , Rong-Gen Cai

We study gravitational wave production in an expanding Universe during the first stages following inflation, and investigate the consequences of the Gauss-Bonnet term on the inflationary parameters for a power-law inflation model with a GB…

General Relativity and Quantum Cosmology · Physics 2022-09-20 K. El Bourakadi , M. Ferricha-Alami , H. Filali , Z. Sakhi , M. Bennai

We study the effects of the Gauss-Bonnet term on the energy spectrum of inflationary gravitational waves. The models of inflation are classified into two types based on their predictions for the tensor power spectrum: red-tilted ($n_T<0$)…

Cosmology and Nongalactic Astrophysics · Physics 2018-11-15 Seoktae Koh , Bum-Hoon Lee , Gansukh Tumurtushaa

We theoretically and observationally investigate different choices of initial conditions for the primordial mode function that are imposed during an epoch preceding inflation. By deriving predictions for the observables resulting from…

Cosmology and Nongalactic Astrophysics · Physics 2021-09-23 T. Gessey-Jones , W. J. Handley

Warm inflation dynamics is fundamentally based on a system-reservoir configuration in which the dynamics is dictated by a fluctuation-dissipation relation. Recent work by Cerioni et. al. (arXiv:0804.0163) examined dissipative dynamics with…

Astrophysics · Physics 2008-05-15 Arjun Berera , Lisa M. H. Hall , Ian G. Moss , Hiranya V. Peiris

The amplitude of primordial curvature perturbations is enhanced when a radiation bath at a temperature T>H is sustained during inflation by dissipative particle production, which is particularly significant when a non-trivial statistical…

High Energy Physics - Phenomenology · Physics 2014-04-03 Sam Bartrum , Mar Bastero-Gil , Arjun Berera , Rafael Cerezo , Rudnei O. Ramos , Joao G. Rosa