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We revisit higher order corrections to the Starobinsky inflationary model using the most recent P-ACT-LB-BK18 data, which exhibits a mild but definite tension with the predictions of the original model. Our results demonstrate how even…

High Energy Physics - Phenomenology · Physics 2026-02-23 Min Gi Park , Dhong Yeon Cheong , Seong Chan Park

We have revisited quasi-exponential model of inflation in the light of recent ACT-DR6 and Planck data along with latest constraint on the amplitude of primordial gravitational waves. For our analysis we have followed Mukhanov approach for…

Cosmology and Nongalactic Astrophysics · Physics 2025-12-12 Barun Kumar Pal

We examine the power-law Starobinsky model, a generalized version of the Starobinsky inflation model, characterized by a power-law correction to Einstein gravity. Employing the $f(R)$ formalism, the scalar and tensor power spectra were…

Cosmology and Nongalactic Astrophysics · Physics 2025-02-10 Saisandri Saini , Akhilesh Nautiyal

Recent measurements from the Atacama Cosmology Telescope (ACT), combined with Planck and DESI data, suggest a higher value for the spectral index $n_s$. This places Starobinsky inflation at the edge of the $2\sigma$ constraints for a number…

Cosmology and Nongalactic Astrophysics · Physics 2025-09-23 Manuel Drees , Yong Xu

The combination of the data from the Dark Energy Spectroscopic Instrument (DESI) with the recent measurements from the Atacama Cosmology Telescope (ACT) indicate that the scalar spectral index \( n_s \) has a larger value than the Planck…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-02 Jureeporn Yuennan , Farruh Atamurotov , Phongpichit Channuie

We analyze the latest cosmic microwave background (CMB) constraints on the scalar spectral index $n_s$ and tensor-to-scalar ratio $r$ from Planck 2018, BICEP/Keck 2018, the Atacama Cosmology Telescope Data Release 6 (ACT DR6), and the South…

High Energy Physics - Phenomenology · Physics 2025-10-22 John Ellis , Marcos A. G. Garcia , Keith A. Olive , Sarunas Verner

We revisit the Starobinsky model of inflation in light of recent data from the Atacama Cosmology Telescope (ACT), which indicates a potential preference for a slightly larger scalar spectral index $n_s$ than predicted by the standard $R^2$…

General Relativity and Quantum Cosmology · Physics 2025-12-25 Andrea Addazi , Yermek Aldabergenov , Daulet Berkimbayev , Yifu Cai

After reviewing the motivations for cosmological inflation formulated in the formalism of supersymmetry, we argue that the appropriate framework is that of no-scale supergravity. We then show how to construct within this framework…

High Energy Physics - Phenomenology · Physics 2021-02-24 John Ellis , Marcos A. G. Garcia , Natsumi Nagata , Dimitri V. Nanopoulos , Keith A. Olive , Sarunas Verner

We consider quantum corrections to a recently obtained perturbative form of Starobinsky model to extract information about the initial conditions of the universe leading to cosmological inflation. Integrating out graviton modes, we find…

General Relativity and Quantum Cosmology · Physics 2025-12-02 Abhijith Ajith , Hardik Jitendra Kuralkar , Sukanta Panda , Archit Vidyarthi

In this work we revisit $\alpha$-Starobinsky inflation, also know as $E$-model, in the light of current CMB and LSS observations. The inflaton potential in the Einstein frame for this model contains a parameter $\alpha$ in the exponential,…

Cosmology and Nongalactic Astrophysics · Physics 2025-07-11 Saisandri Saini , Akhilesh Nautiyal

We place observational constraints on slow-variation single-field inflationary models by carrying out the cosmological Monte Carlo simulation with the recent data of Planck combined with the WMAP large-angle polarization, baryon acoustic…

Cosmology and Nongalactic Astrophysics · Physics 2013-11-12 Shinji Tsujikawa , Junko Ohashi , Sachiko Kuroyanagi , Antonio De Felice

In this paper we perform a global analysis of the constraints on the inflationary parameters in the presence of dynamical dark energy models from the current observations, including the three-year Wilkinson Microwave Anisotropy Probe…

Astrophysics · Physics 2008-11-26 Jun-Qing Xia , Xinmin Zhang

The latest CMB data from ACT DR6, combined with Planck, DESI, and BICEP/Keck, indicate a slight upward shift in the scalar spectral index, placing several previously favored inflationary models under tension. We study an inflationary…

General Relativity and Quantum Cosmology · Physics 2025-11-26 Z. Ossoulian , T. Golanbari , Kh. Saaidi

We present a joint Bayesian analysis to impose constraints on the generalized $\alpha$-Starobinsky inflationary model using the high-precision cosmological datasets: Planck, CMB lensing from ACT DR6, and Baryon Acoustic Oscillations (BAO)…

Cosmology and Nongalactic Astrophysics · Physics 2026-03-27 Karim Carrion , Francisco X. Linares Cedeño , Gabriel Germán , Juan Carlos Hidalgo

Starobinsky has suggested an inflation model which is obtained from the vacuum Einstein's equations modified by the one-loop corrections due to quantized matter fields. Although the one-loop gravitational action is not known for a general…

Cosmology and Nongalactic Astrophysics · Physics 2018-04-06 Seokcheon Lee

In the context of effective theories of gravity, a minimalist bottom-up approach which takes into account $1$-loop quantum corrections leads to modifications in the Einstein-Hilbert action through the inclusion of four extra terms: $R^{2}$,…

General Relativity and Quantum Cosmology · Physics 2023-01-27 J. Bezerra-Sobrinho , L. G. Medeiros

We provide a simple yet effective semi-analytical approach to confront Mukhanov Parametrization of inflationary equation-of-state, $1+\omega =\frac{\beta}{({N}+1)^\alpha}$, with the latest ACT-DR6 data employing Hamilton-Jacobi formulation.…

Cosmology and Nongalactic Astrophysics · Physics 2026-01-13 Barun Kumar Pal

In this work we study four well-known inflationary scenarios that are reported by the most recent Planck observations: Natural inflation, Hilltop quartic inflation, Starobinsky inflationary model, and Large field power-law potentials…

General Relativity and Quantum Cosmology · Physics 2024-04-30 Daniel Pozo , Jordan Zambrano , Ismael Villegas , Rafael Hernández-Jiménez , Clara Rojas

In this work we consider a generalization of Starobinsky inflation obtained by combining power law ($R^\beta$), and $\alpha$-Starobinsky inflation ($E$-model). The Einstein frame potential for this model is that of power law Starobinsky…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-25 Saisandri Saini , Akhilesh Nautiyal

We update the constraints on the power spectra of primordial curvature perturbation and tensor perturbation including Planck data 2015 (P15) and recently released BICEP2/Keck data (BK15), Baryon Acoustic Oscillation data and the Type Ia…

Cosmology and Nongalactic Astrophysics · Physics 2023-02-15 Jun Li , Qing-Guo Huang