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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

We explored a parameterized slow-roll inflationary model within the $\Lambda$CDM framework, utilizing a combination of data from Planck 2018, ACT DR6, DESI DR2, and BICEP/Keck 2018 (P-ACT-LB-BK18). Additionally, we incorporated the SH0ES…

Cosmology and Nongalactic Astrophysics · Physics 2026-05-20 Zhi-Chong Qiu , Ye-Huang Pang , Qing-Guo Huang

The original Starobinsky $R + R^2$ model of inflation is consistent with Planck and other measurements of the CMB, but recent results from the ACT and SPT Collaborations hint that the tilt of scalar perturbations may be in tension with the…

High Energy Physics - Phenomenology · Physics 2025-08-20 John Ellis , Marcos A. G. Garcia , Natsumi Nagata , Dimitri V. Nanopoulos , Keith A. Olive

We investigate the impact of curvature corrections to Starobinsky inflation in light of the latest observational results from the Atacama Cosmology Telescope (ACT). While the pure Starobinsky model remains a compelling candidate for cosmic…

General Relativity and Quantum Cosmology · Physics 2025-09-18 Andrea Addazi , Yermek Aldabergenov , Sergei V. Ketov

We analyze the Starobinsky inflation model and the impact of curvature corrections, particularly a cubic $R^3$ term, to assess their behavior in light of the latest observational results from the Atacama Cosmology Telescope (ACT). With the…

Cosmology and Nongalactic Astrophysics · Physics 2025-12-30 J. Bezerra-Sobrinho , L. G. Medeiros

Recent measurements from the Atacama Cosmology Telescope (ACT), combined with Planck and DESI data, suggest a scalar spectral index $n_s$ higher than the Planck 2018 baseline, thereby placing conventional attractor-type inflationary models…

Cosmology and Nongalactic Astrophysics · Physics 2025-11-18 Jureeporn Yuennan , Peeravit Koad , Farruh Atamurotov , Phongpichit Channuie

We study several extensions of the Starobinsky model of inflation, which obey all observational constraints on the inflationary parameters, by demanding that both the inflaton scalar potential in the Einstein frame and the $F(R)$ gravity…

General Relativity and Quantum Cosmology · Physics 2022-03-30 Vsevolod R. Ivanov , Sergei V. Ketov , Ekaterina O. Pozdeeva , Sergey Yu. Vernov

The ACT data shows an enhancement in the value of the scalar spectral index, as $n_s = 0.9743 \pm 0.0034$, leading to disfavoring many inflationary models, including the Starobinsky model. To satisfy the constraint made by ACT, we will…

Cosmology and Nongalactic Astrophysics · Physics 2025-05-09 Yogesh , Abolhassan Mohammadi , Qiang Wu , Tao Zhu

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

The $F(R)$ gravity models of inflation are revisited in light of the recent observations of cosmic microwave background radiation by Atacama Cosmology Telescope (ACT) and DESI Collaboration. A detailed study of the evolution equations in…

General Relativity and Quantum Cosmology · Physics 2025-12-18 Sergei V. Ketov , Ekaterina O. Pozdeeva , Sergey Yu. Vernov

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

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

We investigate the implications of recent CMB observations for Higgs-Starobinsky inflationary models and their associated reheating dynamics, utilizing data from ACT DR6, Planck 2018, BICEP/Keck 2018, and DESI, collectively referred to as…

Cosmology and Nongalactic Astrophysics · Physics 2025-09-03 Md Riajul Haque , Sourav Pal , Debarun Paul

In this work, we studied the slow-roll approximation of cosmic inflation within the context of $f(R,T)$ gravity, where $R$ is the scalar curvature, and $T$ is the trace of the energy-momentum tensor. By choosing a minimal coupling between…

General Relativity and Quantum Cosmology · Physics 2021-01-12 Mauricio Gamonal

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 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

We show that quantum-induced marginal deformations of the Starobinsky gravitational action of the form $R^{2(1 -\alpha)}$, with $R$ the Ricci scalar and $\alpha$ a positive parameter, smaller than one half, can account for the recent…

High Energy Physics - Phenomenology · Physics 2015-02-11 A. Codello , J. Joergensen , F. Sannino , O. Svendsen

Data on the cosmic microwave background (CMB) are discriminating between different models of inflation, disfavoring simple monomial potentials whilst being consistent with models whose predictions resemble those of the Starobinsky $R + R^2$…

High Energy Physics - Phenomenology · Physics 2025-04-21 Ignatios Antoniadis , John Ellis , Wenqi Ke , Dimitri V. Nanopoulos , Keith A. Olive

Recent measurements from the Atacama Cosmology Telescope (ACT), particularly when combined with DESI baryon acoustic oscillation data, have reported a scalar spectral index $n_s$ slightly higher than that inferred by {\it Planck}~2018,…

Cosmology and Nongalactic Astrophysics · Physics 2025-11-18 Jureeporn Yuennan , Farruh Atamurotov , Phongpichit Channuie

In this work we examine a theoretical scenario which combines two fundamental theoretical proposals for the early Universe and a possible evolution for the early post-inflationary epoch. Specifically, we assume that the early Universe…

General Relativity and Quantum Cosmology · Physics 2025-09-23 S. D. Odintsov , V. K. Oikonomou
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