Article
Astronomy & Astrophysics
Jerome Martin, Lucas Pinol
Summary: The robustness of multi-field inflation to the physics of reheating is investigated, establishing equations of motion for background and perturbative quantities and emphasizing the importance of tracking perturbations through numerical calculations for precision. Illustrating a physical prediction affected by micro-physics of reheating, the study finds significant differences when ignoring fine-structure of reheating, highlighting the necessity of considering detailed reheating processes in multi-field inflation.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Mio Kubota, Kin-ya Oda, Stanislav Rusak, Tomo Takahashi
Summary: Double inflation can occur when a spectator field is non-minimally coupled to gravity. The non-minimal coupling results in the growth of the spectator field, which drives the second stage of inflation in a significant region of parameter space. The non-minimal coupling of the spectator field can modify the predictions for the spectral index and the tensor-to-scalar ratio.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Lei-Hua Liu, Tomislav Prokopec
Summary: This study investigates scalar cosmological perturbations generated through nonminimal coupling in two-field inflationary models with a focus on curvaton scenarios. It shows that small, negative nonminimal couplings can contribute to a redder curvature spectrum, potentially saving some curvaton scenarios that would otherwise be ruled out. The study also highlights the impact of nonminimal coupling on the postinflationary growth of the spectator perturbation and the effectiveness of the curvaton mechanism.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Ki-Young Choi, Jinn-Ouk Gong, Su-beom Kang, Rathul Nath Raveendran
Summary: This article suggests a new method to reconstruct the inflaton potential directly from the primordial power spectrum within canonical single-field inflation. It introduces a more generalized slow-roll approximation to reliably probe the properties of the inflaton potential. The validity of this method is discussed through several examples.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Danilo Artigas, Julien Grain, Vincent Vennin
Summary: The separate-universe approach provides an effective description of cosmological perturbations, simplifying the analysis of large-scale fluctuations by considering the universe as a collection of independent homogeneous and isotropic regions. This study formulates the separate-universe approach in the Hamiltonian formalism, analyzing the full phase-space structure of perturbations. The research shows that, as long as the wavelengths are larger than a certain lower bound, the separate-universe approach reproduces the same phase-space dynamics as the full cosmological perturbation theory.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Xuce Niu, Moinul Hossain Rahat, Karthik Srinivasan, Wei Xue
Summary: This study extends the reach of the cosmological collider for massive gauge boson production during inflation from the CMB scales to the interferometer scales. By considering a Chern-Simons coupling between the gauge bosons and the pseudoscalar inflaton, the authors show that the presence of massive gauge fields during inflation can be detected from characteristic gravitational wave signals encompassing the whole range of current and planned interferometers.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Ki-Young Choi, Su-beom Kang, Rathul Nath Raveendran
Summary: In this paper, the authors demonstrate how a potential of multi scalar fields can be reconstructed from a given power spectrum to generate a peak in the power spectrum on small scales. The slow-roll of the second field in the curved trajectory is responsible for the generation of this peak through the isocurvature perturbation. The reconstructed potential from multi scalar fields may not be unique and different potentials can be derived from a given power spectrum.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Cesar Gomez, Raul Jimenez
Summary: The most robust prediction of inflation driven by a single field is the existence of a red tilt for the spectrum of curvature fluctuations that is experimentally of order 0.04. This is derived by solving the exact equation for quantum fluctuations in a quasi de Sitter background with a small but non-vanishing first slow-roll parameter. The lack of scale invariance associated with the tilt is classical in essence and parametrized by the slow roll parameter of the inflaton potential. A purely quantum mechanical and model independent derivation of the tilt is presented based on two observations: the correlator for the Mukhanov-Sasaki gauge invariant variables is related to the quantum Fisher function, and this quantum Fisher function has a non-vanishing scale dependent red tilt that fits the effective quasi de Sitter prediction and experimental value at the energy scales of interest.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Aliakbar Abolhasani, Harry Goodhew
Summary: We present a systematic prescription for calculating cosmological correlation functions for models with derivative interactions and compare it with the in-in formalism. By performing path integrals, we show that our method recovers the classical action and includes additional contributions to cancel other divergences.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Lucas Pinol
Summary: This article explores linear dynamics and cubic interactions for N-field scalar fields during inflation, using observable curvature perturbations and entropic fluctuations. It reveals rich geometrical effects beyond scalar curvature, particularly when the field space dimension is larger than two. The article also highlights potential instability in background dynamics when N-field is greater than or equal to 3, due to negative eigenvalues in the entropic mass matrix from fast rotation of local entropic basis.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Alberto Nicolis, Guanhao Sun
Summary: In the context of icosahedral inflation, the mixed scalar-tensor two-point function is expected to be perturbatively small within the effective field theory, but it can be significantly larger than the tensor spectrum. Observational implications for the CMB temperature-polarization spectrum are discussed.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Marios Bounakis, Ian G. Moss, Gerasimos Rigopoulos
Summary: The study provides a concise treatment of the evolution in a Hyperinflation model, finding that the adiabatic spectral index severely restricts the values of the potential's slope.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Yoelsy Leyva, Giovanni Otalora
Summary: This article studies inflation and the generation of primordial fluctuations in f (R) gravity's rainbow. The cosmological perturbations and the scalar and tensor primordial power spectrum are calculated. The predictions of the model are contrasted with current observational data from PLANCK and BICEP/Keck. New results for the scalar spectral index ns and the tensor-to-scalar ratio r are found, along with new observational constraints on the rainbow functions.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Michal Artymowski, Ido Ben-Dayana, Udaykrishna Thattarampilly
Summary: The study introduces generic conditions for the slow contracting Universe and fast-roll models, focusing on freeze-out of perturbations and the sourced bounce scenario. It is shown that a viable slightly red scalar spectrum can be achieved, but the tensor-to-scalar ratio in fast-roll models is generally inconsistent with current observations, requiring a different approach for a successful Sourced Bounce.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Sayantan Choudhury, Sudhakar Panda, M. Sami
Summary: In this study, we provide a detailed analysis of the formation of Primordial Black Holes (PBHs) during Slow Roll (SR) to Ultra Slow Roll (USR) sharp transitions in the framework of single-field inflation using an effective field theory (EFT) approach. Our results show that the prospects for PBH formation are severely limited in a single-field inflationary framework when renormalizing the power spectrum to one loop order in P(X, phi) theories. We also demonstrate that the addition of an SR regime after USR before the end of inflation does not significantly change our conclusions. Moreover, our findings strictly rule out the possibility of generating large masses of PBHs from all possible models of single field inflation (canonical and non-canonical).
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Lucia Fonseca de la Bella, Donough Regan, David Seery, Shaun Hotchkiss
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2017)
Article
Astronomy & Astrophysics
Ricardo Z. Ferreira, McCullen Sandora, Martin S. Sloth
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2017)
Article
Astronomy & Astrophysics
Joyce Byun, Alexander Eggemeier, Donough Regan, David Seery, Robert E. Smith
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2017)
Article
Astronomy & Astrophysics
Ricardo Z. Ferreira, McCullen Sandora, Martin S. Sloth
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2018)
Article
Astronomy & Astrophysics
Mathias Garny, Andrea Palessandro, McCullen Sandora, Martin S. Sloth
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2018)
Article
Astronomy & Astrophysics
Sean Butchers, David Seery
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2018)
Article
Astronomy & Astrophysics
Mathias Garny, Andrea Palessandro, McCullen Sandora, Martin S. Sloth
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2019)
Article
Astronomy & Astrophysics
Lucia Fonseca de la Bella, Donough Regan, David Seery, David Parkinson
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2020)
Article
Astronomy & Astrophysics
Michaela G. Lawrence, David Seery, Christian T. Byrnes
Summary: The study explores a disformal coupling between Standard Model matter and a cubic Galileon scalar sector, which evades strict constraints from the integrated Sachs-Wolfe effect. Despite the presence of a cosmological 'screening-like' phenomenon, the disformal coupling is too weak to be constrained by recent events such as GW170817 or by the dispersion of electromagnetic radiation at different wavelengths.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Kareem Marzouk, Alessandro Maraio, David Seery
Summary: In this study, we update predictions for observables in the "delicate" D3/(D3) over bar inflationary model on the conifold. Our analysis shows that the model can accurately forecast the amplitude of three-point correlations. The model generally follows Maldacena's single-field prediction, but in some cases, the bispectrum is dominated by effects from rapid switching between angular minima, resulting in larger amplitudes but with unacceptable spectral behavior.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Michaela G. Lawrence, David Seery
Summary: This study revisits the sequester proposal, evaluates different formulations, and finds a particular class of quantum corrections to be important. In formulations that do not adequately sequester graviton loops, dressing of interactions leads to further failures of complete sequestration, but the effect is typically smaller than the cosmological term induced by single virtual graviton loops. In the most developed scenario, dressing can be absorbed into a resealing of rigid fields, making it harmless.
Article
Astronomy & Astrophysics
Florian Niedermann, Martin S. Sloth
Article
Astronomy & Astrophysics
Takeshi Kobayashi, Martin S. Sloth
Article
Astronomy & Astrophysics
Niklas G. Nielsen, Andrea Palessandro, Martin S. Sloth
Article
Astronomy & Astrophysics
Clare Burrage, David Parkinson, David Seery