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It is known that if the standard slow-roll inflation is followed by a power-law inflationary regime, then the trans-Planckian modes may be safely be contained in the Hubble horizon and never exit it during inflation. In this work we…

General Relativity and Quantum Cosmology · Physics 2026-01-29 S. D. Odintsov , V. K. Oikonomou

We argue that the non-detection of primordial tensor modes has taught us a great deal about the primordial universe. In single-field slow-roll inflation, the current upper bound on the tensor-to-scalar ratio, $r < 0.07$ $(95 \% ~CL)$,…

High Energy Physics - Theory · Physics 2017-06-21 Enrico Pajer , Guilherme L. Pimentel , Jaap V. S. Van Wijck

Renormalization of quantum loop effects generated from large fluctuations is a hugely debatable topic of research these days which rules out the Primordial Black Hole (PBH) formation within the framework of single-field inflation. In this…

Cosmology and Nongalactic Astrophysics · Physics 2024-10-10 Sayantan Choudhury

We present a complete and consistent exposition of the regularization, renormalization, and resummation procedures in the setup of having a contraction and then non-singular bounce followed by inflation with a sharp transition from…

Cosmology and Nongalactic Astrophysics · Physics 2024-11-28 Sayantan Choudhury , Ahaskar Karde , Sudhakar Panda , Soumitra SenGupta

The ability to infer properties of primordial inflation relies on the conservation of the superhorizon perturbations between their exit during inflation, and their re-entry during radiation era. Any considerable departure from this property…

Cosmology and Nongalactic Astrophysics · Physics 2025-12-29 Markus B. Fröb , Dražen Glavan , Paolo Meda , Ignacy Sawicki

Inflation is the leading paradigm for explaining the origin of primordial density perturbations and the observed temperature fluctuations of the cosmic microwave background. However many open questions remain, in particular whether one or…

High Energy Physics - Theory · Physics 2015-06-05 Gianmassimo Tasinato , Christian T. Byrnes , Sami Nurmi , David Wands

According to the equivalence principal, the long wavelength perturbations must not have any dynamical effect on the short scale physics up to ${\cal O} (k_L^2/k_s^2)$. Their effect can be always absorbed to a coordinate transformation…

Cosmology and Nongalactic Astrophysics · Physics 2018-08-29 Ali Akbar Abolhasani , Misao Sasaki

Strongly supercooled first-order phase transitions have been proposed as a primordial black hole (PBH) production mechanism. While previous works rely on simplified models with limited thermodynamic precision, we stress that reliable…

High Energy Physics - Phenomenology · Physics 2026-05-25 Maciej Kierkla , Nicklas Ramberg , Philipp Schicho , Daniel Schmitt

The quantum-to-classical transition of inflationary perturbations remains an unresolved fundamental problem, and quantum decoherence is one of the promising solutions. By considering quantum perturbations during inflation as an open quantum…

General Relativity and Quantum Cosmology · Physics 2025-07-01 Zhongkai Wang , Yungui Gong

In non-attractor single-field inflation models producing a scale-invariant power spectrum, the curvature perturbation on super-horizon scales grows as ${\cal R}\propto a^3$. This is so far the only known class of self-consistent…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-17 Xingang Chen , Hassan Firouzjahi , Eiichiro Komatsu , Mohammad Hossein Namjoo , Misao Sasaki

We consider the impact of quantum diffusion on inflationary dynamics during an ultra-slow-roll phase, which can be of particular significance for the formation of primordial black holes. We show, by means of a fully analytical approach,…

Cosmology and Nongalactic Astrophysics · Physics 2020-09-02 Guillermo Ballesteros , Julián Rey , Marco Taoso , Alfredo Urbano

In this work, we investigate the generation of primordial black holes (PBHs) within the framework of single-field inflationary models and their compatibility with the cosmological history of the Universe. Our results suggest that, depending…

Cosmology and Nongalactic Astrophysics · Physics 2025-06-30 Sasha Allegrini , Loris Del Grosso , Antonio J. Iovino , Alfredo Urbano

In the Horndeski's most general scalar-tensor theories, we derive the three-point correlation function of scalar non-Gaussianities generated during single-field inflation in the presence of slow-variation corrections to the leading-order…

High Energy Physics - Theory · Physics 2015-06-12 Antonio De Felice , Shinji Tsujikawa

In response to a recent criticism, appeared in arXiv:2303.00341, we argue that the standard scenario to form primordial black holes in the early universe based on a phase of ultra-slow-roll in single-field inflation is not ruled out.

Cosmology and Nongalactic Astrophysics · Physics 2023-03-06 A. Riotto

We study single-field inflationary models with steep step-like features in the potential that lead to the temporary violation of the slow-roll conditions during the evolution of the inflaton. These features enhance the power spectrum of the…

Cosmology and Nongalactic Astrophysics · Physics 2022-02-18 I. Dalianis , G. P. Kodaxis , I. D. Stamou , N. Tetradis , A. Tsigkas-Kouvelis

Slow-roll inflation is studied in theories where the inflaton field is conformally coupled to the Ricci scalar. In particular, the case of Higgs field inflation in the context of the noncommutative spectral action is analyzed. It is shown…

High Energy Physics - Theory · Physics 2010-08-31 Michel Buck , Malcolm Fairbairn , Mairi Sakellariadou

A broad range of single field models of inflation are analyzed in light of all relevant recent cosmological data, checking whether they can lead to the formation of long-lived Primordial Black Holes (PBHs). To that end we calculate the…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 Manuel Drees , Encieh Erfani

All single-field inflationary models invoke varying degrees of tuning in order to account for cosmological observations. Mechanisms that generate primordial black holes (PBHs) from enhancement of primordial power at small scales posit…

Cosmology and Nongalactic Astrophysics · Physics 2023-08-17 Philippa S. Cole , Andrew D. Gow , Christian T. Byrnes , Subodh P. Patil

Ultra slow-roll inflation has recently been used to challenge the non-Gaussianity consistency relation. We show that this inflationary scenario belongs to a one parameter class of models and we study its properties and observational…

Cosmology and Nongalactic Astrophysics · Physics 2013-05-30 Jerome Martin , Hayato Motohashi , Teruaki Suyama

We investigate constraints on power spectra of the primordial curvature and tensor perturbations with priors based on single-field slow-roll inflation models. We stochastically draw the Hubble slow-roll parameters and generate the…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-20 Masahiro Kawasaki , Toyokazu Sekiguchi