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In this work, we present a quintessential interpretation of having a blue-tilted tensor power spectrum for canonical single-field slow-roll inflation to explain the recently observed Pulsar Timing Array (NANOGrav 15-year and EPTA) signal of…

Cosmology and Nongalactic Astrophysics · Physics 2024-03-19 Sayantan Choudhury

We investigate a class of slow roll inflationary models in the light of the recent Cosmic Microwave Background constraints from Planck 2018, ACT DR6, DESI DR1, and BICEP/\textit{Keck} 2018. The combined dataset favors a higher value of the…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-08 Suvashis Maity

NANOGrav and various pulsar timing array experiments recently reported evidence for a common red noise signal across millisecond pulsars. This signal exhibits Hellings-Downs inter-pulsar correlation patterns, providing compelling evidence…

Cosmology and Nongalactic Astrophysics · Physics 2026-05-08 Debtosh Chowdhury , Rounak Nath , Sudipta Show

The reconstruction of a braneworld inflationary universe considering the parametrization (or attractor) of the scalar spectral index $n_s(N)$ in terms of the number of $e$-foldings N is developed. We also study the possibility that the…

General Relativity and Quantum Cosmology · Physics 2019-05-15 Ramon Herrera

We examine the effects of a stiff pre-recombination era on the present day's energy spectrum of the primordial gravitational waves. If the background total equation of state parameter at the pre-recombination era is described by a kination…

Cosmology and Nongalactic Astrophysics · Physics 2023-11-02 V. K. Oikonomou

When modelling inflaton fluctuations as a free quantum scalar field, the initial vacuum is conventionally imposed at the infinite past. This is called the Bunch-Davies (BD) vacuum. If however an asymptotically Minkowskian past does not…

High Energy Physics - Theory · Physics 2016-11-14 Benedict J. Broy

In this work we study models of anisotropic inflation with the generalized non-vacuum initial states for the inflaton field and the gauge field. The effects of non Bunch-Davies initial condition on the anisotropic power spectrum and…

High Energy Physics - Theory · Physics 2014-07-09 Razieh Emami , Hassan Firouzjahi , Moslem Zarei

Inspired by the reconstruction scheme of the inflaton field potential $V(\phi)$ from the attractors$n_s(N)$, we investigate the viability of reconstruct the inflationary potential within the framework of k-inflation for a non-linear kinetic…

General Relativity and Quantum Cosmology · Physics 2023-05-10 Ramon Herrera , Michel Housset , Constanza Osses , Nelson Videla

In this paper my prime objective is to analyze the constraints on a sub-Planckian excursion of a single inflaton field within Effective Field Theory framework in a model independent fashion. For a generic single field inflationary…

Cosmology and Nongalactic Astrophysics · Physics 2015-12-02 Sayantan Choudhury

We derive the reconstruction formulae for the inflation model with the non-minimal derivative coupling term. If reconstructing the potential from the tensor-to-scalar ratio, we could obtain the potential without using the high friction…

General Relativity and Quantum Cosmology · Physics 2020-11-23 Qin Fei , Zhu Yi , Yingjie Yang

In this paper we will analyse the constraints on a sub-Planckian excursion of a single inflaton field, which would yield a large tensor to scalar ratio, while explaining the temperature anisotropy of the cosmic microwave background (CMB)…

High Energy Physics - Theory · Physics 2014-04-01 Sayantan Choudhury , Anupam Mazumdar

We present constraints on canonical single-field inflation derived from WMAP five year, ACBAR, QUAD, BICEP data combined with the halo power spectrum from SDSS LRG7. Models with a non-scale-invariant spectrum and a red tilt n_s < 1 are now…

Cosmology and Nongalactic Astrophysics · Physics 2010-04-30 Fabio Finelli , Jan Hamann , Samuel M. Leach , Julien Lesgourgues

The recently relased \emph{Planck} data, emphasize that the background geometry of inflation is not pure de Sitter, but from the slow variation of Hubble parameter during the inflationary era, it can be quasi-de Sitter. This motivates us to…

Cosmology and Nongalactic Astrophysics · Physics 2018-04-09 Hossein Moshafi , Ata Sojasi , Ebrahim Yusofi , Majid Mohsenzadeh

We show that it is possible to simulate realistic inhomogeneities during cosmological inflation with high precision using {Numerical Relativity}. Stochastic initial conditions are set in line with the Bunch-Davies {vacuum} and satisfy the…

General Relativity and Quantum Cosmology · Physics 2025-07-24 Yoann L. Launay , Gerasimos I. Rigopoulos , E. Paul S. Shellard

During the inflationary epoch, we investigate the reconstruction of the background variables within the framework of Einstein-Gauss-Bonnet gravity, considering the scalar spectral index $n_s(N)$ and the tensor-to-scalar ratio $r(N)$, where…

General Relativity and Quantum Cosmology · Physics 2026-01-28 Ramón Herrera , Carlos Ríos

We compute a novel type of large non-Gaussianity due to small periodic features in general single field inflationary models. We show that the non-Bunch-Davies vacuum component generated by features, although has a very small amplitude, can…

High Energy Physics - Theory · Physics 2010-12-09 Xingang Chen

We use cosmic microwave background and large scale structure data to test a broad and physically well-motivated class of inflationary models: those with flat tree-level potentials (typical in supersymmetry). The non-trivial features of the…

High Energy Physics - Phenomenology · Physics 2009-03-24 G. Ballesteros , J. A. Casas , J. R. Espinosa , R. Ruiz de Austri , R. Trotta

We provide a refined and much more simplified Einstein-Gauss-Bonnet inflationary theoretical framework, which is compatible with the GW170817 observational constraints on the gravitational wave speed. As in previous works, the constraint…

General Relativity and Quantum Cosmology · Physics 2021-09-22 V. K. Oikonomou

In this paper the focus is on inflationary dynamics in the context of Einstein Gauss-Bonnet gravitational theories. We investigate the implications of the slow-roll condition on the slow-roll indices and we investigate how the inflationary…

General Relativity and Quantum Cosmology · Physics 2018-09-26 S. D. Odintsov , V. K. Oikonomou

In this paper, we apply reconstruction techniques to recover the potential parameters for a particular class of single-field models, the $\alpha$-attractor (supergravity) models of inflation. This also allows to derive the inflaton vacuum…

Cosmology and Nongalactic Astrophysics · Physics 2017-03-28 A. Di Marco , P. Cabella , N. Vittorio
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