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We consider a power law $\frac{1}{M^2}R^{\beta}$ correction to Einstein gravity as a model of inflation. The interesting feature of this form of generalization is that small deviations from the Starobinsky limit $\beta=2$ can change the…

High Energy Physics - Phenomenology · Physics 2015-06-11 Girish Kumar Chakravarty , Subhendra Mohanty

Recently we have studied in great detail a model of Hybrid Natural Inflation (HNI) by constructing two simple effective field theories. These two versions of the model allow inflationary energy scales as small as the electroweak scale in…

Cosmology and Nongalactic Astrophysics · Physics 2017-07-06 Gabriel German , Alfredo Herrera--Aguilar

We explore the inflationary evolution and observational viability of the $\alpha$-attractor E-model in the framework of warm inflation, focusing on both weak and strong dissipative regimes, with a dissipation coefficient linear in…

Cosmology and Nongalactic Astrophysics · Physics 2025-06-10 Bhargabi Saha , Malay K. Nandy

We consider two non-canonical scalar fields (tachyon and DBI) with E-model type of the potential. We study cosmological inflation in these models to find possible $\alpha$-attractors. We show that similar to the canonical scalar field case,…

Cosmology and Nongalactic Astrophysics · Physics 2018-05-23 Narges Rashidi , Kourosh Nozari

We investigate the observational constraints on $\alpha$-attractor inflationary models and their post-inflationary reheating dynamics in light of the latest CMB data from ACT DR6 combined with Planck18, BICEP/$Keck$ 2018, and DESI…

Cosmology and Nongalactic Astrophysics · Physics 2025-05-06 Md Riajul Haque , Sourav Pal , Debarun Paul

Hilltop inflation models are often described by potentials $V = V_{0}(1-{\phi^{n}\over m^{n}}+...)$. The omitted terms indicated by ellipsis do not affect inflation for $m \lesssim 1$, but the most popular models with $n =2$ and $4$ for $m…

High Energy Physics - Theory · Physics 2019-09-25 Renata Kallosh , Andrei Linde

The reconstruction of a warm inflationary universe model from the scalar spectral index $n_S(N)$ and the tensor to scalar ratio $r(N)$ as a function of the number of e-folds $N$ is studied. Under a general formalism we find the effective…

General Relativity and Quantum Cosmology · Physics 2018-04-18 Ramon Herrera

We describe a way to construct supergravity models with an arbitrary inflaton potential V ({\phi}) and show that all other scalar fields in this class of models can be stabilized at the inflationary trajectory by a proper choice of the…

High Energy Physics - Theory · Physics 2011-02-18 Renata Kallosh , Andrei Linde , Tomas Rube

We examine inflationary universe models driven by scalar fields with logarithmic potentials of the form $V(\phi) = V_0 \phi^p(\ln \phi)^q$. Combining the slow-roll approximation with asymptotic techniques, we identify regions of the…

Astrophysics · Physics 2009-10-28 John D. Barrow , Paul Parsons

Inflection-point inflation is an interesting possibility to realize a successful slow-roll inflation when inflation is driven by a single scalar field with its initial value below the Planck mass ($\phi_I \lesssim M_{Pl}$). In order for a…

High Energy Physics - Phenomenology · Physics 2017-03-08 Nobuchika Okada , Digesh Raut

Recent observations from the Atacama Cosmology Telescope (ACT) indicate a moderate upward shift in the scalar spectral index $n_s$ compared to Planck $2018$, thereby placing tighter constraints on inflationary scenarios. Motivated by these…

Cosmology and Nongalactic Astrophysics · Physics 2025-08-25 Li-Yang Chen , Rongrong Zha , Feng-Yi Zhang

We consider Higgs inflation with an $\alpha R^2$ term. It adds a new scalar degree of freedom, which leads to a two-field model of inflation. We do a complete slow-roll analysis of the three-dimensional parameter space of the $R^2$…

Cosmology and Nongalactic Astrophysics · Physics 2020-01-22 Vera-Maria Enckell , Kari Enqvist , Syksy Rasanen , Lumi-Pyry Wahlman

A second order pole in the scalar kinetic term can lead to a class of inflation models with universal predictions referred to as pole inflation or $\alpha$-attractors. While this kinetic structure is ubiquitous in supergravity effective…

High Energy Physics - Theory · Physics 2019-03-11 Mafalda Dias , Jonathan Frazer , Ander Retolaza , Marco Scalisi , Alexander Westphal

A simple model of quintessential inflation with the modified exponential potential exp(-\alpha \phi) [A + (\phi-\phi_0)^2] is analyzed in the braneworld context. Considering reheating via instant preheating, it is shown that the evolution…

Astrophysics · Physics 2008-11-26 M. C. Bento , R. Gonzalez Felipe , N. M. C. Santos

Recent observations of cosmic microwave background (CMB) anisotropies combined with large-scale structure may point towards higher values of the scalar spectral index, $n_s$. This puts previously preferred inflationary models, such as…

Cosmology and Nongalactic Astrophysics · Physics 2025-11-19 Laura Iacconi , Sukannya Bhattacharya , Matteo Fasiello , David Wands

The study of reheating in inflationary models is crucial for understanding the early universe and gaining insights into inflationary dynamics and parameters. The reheating temperature $T_{re}$ and the duration of the reheating phase,…

Cosmology and Nongalactic Astrophysics · Physics 2024-04-02 Gabriel German , Juan Carlos Hidalgo , Luis E. Padilla

We study a simple extension of Linde's hybrid inflation model, with the inflaton mass term replaced by the most general renormalizable potential for $\phi$. The unprocessed power spectrum of density perturbations can have two minima and one…

Astrophysics · Physics 2009-10-22 Yun Wang

A simple realization of inflation consists of adding the following operators to the Einstein-Hilbert action: (partial phi)^2, lambda phi^4, and xi phi^2 R, with xi a large non-minimal coupling. Recently there has been much discussion as to…

High Energy Physics - Phenomenology · Physics 2010-12-01 Mark P. Hertzberg

We construct the simplest inflationary $\alpha$-attractor models in supergravity: it has only one scalar, the inflaton. There is no sinflaton since the inflaton belongs to an orthogonal nilpotent superfield where the sinflaton depends on…

High Energy Physics - Theory · Physics 2019-05-01 Renata Kallosh , Yusuke Yamada

Warm inflation is, as of today, one of the best motivated mechanisms for explaining an early inflationary period. In this paper, we derive and analyze the current bounds on warm inflation with a monomial potential $U\propto \phi^p$, using…

Cosmology and Nongalactic Astrophysics · Physics 2016-08-17 Luca Visinelli
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