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Starobinsky inflation and nonminimally coupled (NMC) Higgs inflation have been among the most favored models of the early Universe, as their predictions for the scalar spectral index $n_s$ and tensor-to-scalar ratio $r$ fall comfortably…

Cosmology and Nongalactic Astrophysics · Physics 2025-11-26 Ioannis D. Gialamas , Alexandros Karam , Antonio Racioppi , Martti Raidal

The Atacama Cosmology Telescope (ACT) has recently reported updated measurements of the scalar spectral index $n_s$, revealing a tension with the predictions of many conventional inflationary models. In this work, we adopt a…

Cosmology and Nongalactic Astrophysics · Physics 2025-11-13 Zhu Yi , Xingzhi Wang , Qing Gao , Yungui Gong

We study a new anisotropic inflation model, with an inflaton field nonminimally coupled with the gravity and a vector field. We find that the anisotropic attractor solution exists not only in the weak curvature coupling limit, but more…

General Relativity and Quantum Cosmology · Physics 2015-06-19 Bin Chen , Zhuang-wei Jin

The recently released data from the $\textit{Atacama Cosmology Telescope}$ (ACT) confirms that the primordial scalar spectrum is extremely flat. This, together with current upper bounds on the tensor-to-scalar ratio, implies that the…

High Energy Physics - Theory · Physics 2025-11-24 Arjun Berera , Suddhasattwa Brahma , Zizang Qiu , Rudnei O. Ramos , Gabriel S. Rodrigues

By starting with a two-fields model in which the fields and their derivatives are nonminimally coupled to gravity, and then by using a conformal gauge, we obtain a model in which the derivatives of the canonically normalized field are…

Cosmology and Nongalactic Astrophysics · Physics 2018-08-23 Kourosh Nozari , Narges Rashidi

Here, a single field inflationary model driven by a mutated hilltop potential, a subclass of the hilltop models of inflation, is investigated. To constrain the parameter space, we employ the latest $r-n_{\rm s}$ constraints from Planck…

Cosmology and Nongalactic Astrophysics · Physics 2025-11-11 Iraj Safaei , Soma Heydari , Milad Solbi , Kayoomars Karami

We present a comprehensive analysis of inflationary models in light of projected sensitivities from forthcoming CMB and gravitational wave experiments, incorporating data from recent ACT DR6, DESI DR2, CMB-S4, LiteBIRD, and SPHEREx.…

Cosmology and Nongalactic Astrophysics · Physics 2026-03-17 Sayantan Choudhury , Gulnur Bauyrzhan , Swapnil Kumar Singh , Koblandy Yerzhanov

We study $\alpha$-attractor models with both E-model and T-model potential in an extended Non-Minimal Derivative (NMD) inflation where a canonical scalar field and its derivatives are non-minimally coupled to gravity. We calculate the…

Cosmology and Nongalactic Astrophysics · Physics 2022-04-19 Raheleh Shojaee , Kourosh Nozari , Farhad Darabi

We develop a new class of cosmological attractors which are compatible with the recent ACT results. They are based on two types of fractional Kaehler potentials, K, for a gauge-singlet inflaton phi which reduce, along the inflationary path,…

High Energy Physics - Phenomenology · Physics 2025-10-03 C. Pallis

The $\alpha$-attractor models of inflation have remained one of the preferred inflationary models for nearly a decade now. The unique attractor nature of these models in the $n_s-r$ plane have put these models in the sweet-spot of the…

Cosmology and Nongalactic Astrophysics · Physics 2025-09-04 Dibya Chakraborty , Suratna Das

The recent measurements from the Atacama Cosmology Telescope (ACT) favor a higher value of the scalar spectral index $n_s$ compared to the Planck data, challenging many well-established inflationary models. In this work, we investigate the…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-27 Zhi-Zhang Peng , Zu-Cheng Chen , Lang Liu

Recent ACT data favor a higher scalar spectral index $n_s$, placing models such as $\alpha$-attractor T-models and natural Inflation in tension with current observations. We propose a K-inflation framework with a field-dependent…

General Relativity and Quantum Cosmology · Physics 2026-05-05 Milad Solbi , Daris Samart , Peera Simakachorn

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

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

A field kinetic coupling with the Einstein tensor leads to a gravitationally enhanced friction during inflation, by which even steep potentials with theoretically natural model parameters can drive cosmic acceleration. In the presence of…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 Shinji Tsujikawa

We show explicitly how the T-model, E-model, and Hilltop inflations are obtained from the inflation models with a non-canonical kinetic term and an arbitrary potential. By this method, any attractor of observables $n_s$ and $r$ is possible.…

General Relativity and Quantum Cosmology · Physics 2021-06-22 Zhu Yi , Zong-Hong Zhu

We investigate the observational viability of a class of $\alpha$-attractors inflationary models in light of the most recent Cosmic Microwave Background (CMB) and Large-Scale Structure (LSS) data. By considering a double-well potential we…

Cosmology and Nongalactic Astrophysics · Physics 2021-03-04 J. G. Rodrigues , S. Santos da Costa , J. S. Alcaniz

Due to universality and attractor properties, $\alpha$-attractor quintessential inflation establishes direct relations between inflationary observables such as the scalar tilt $n_s$ and the tensor-to-scalar ratio $r$, and late-time dark…

Cosmology and Nongalactic Astrophysics · Physics 2024-11-26 William Giarè , Eleonora Di Valentino , Eric V. Linder , Enrico Specogna

We present a comprehensive study of warm hybrid inflation within the framework of $\alpha$-attractor models, where an axionic inflaton is coupled to a waterfall field in the presence of thermal dissipation. The model is analyzed for both…

High Energy Physics - Phenomenology · Physics 2026-01-16 Waqas Ahmed , Waqar Ahmad , Ahsan Illahi , M. Junaid

We analyze in a systematic way the implications for the classes of hilltop and hilltop-squared inflation of the recent DR6 observations by the Atacama Cosmology Telescope collaboration. We find that the reported shift in the spectral index…

Cosmology and Nongalactic Astrophysics · Physics 2025-07-22 Monika Lynker , Rolf Schimmrigk