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Astronomy & Astrophysics
Lucas Pinol, Sebastien Renaux-Petel, Yuichiro Tada
Summary: This paper addresses the issues in stochastic inflation theory by using Stratonovich discretization satisfying general covariance and identifying the quantum nature of fluctuating fields leading to the existence of preferred frame defining independent stochastic noises. Physically equivalent Ito-Langevin equations are derived which are manifestly covariant and well suited for numerical computations.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
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Indrani Banerjee, Tanmoy Paul, Soumitra SenGupta
Summary: This study investigates how the interaction between the radion potential and kinetic term in a warped braneworld scenario leads to the transition of the universe from a contracting to an expanding phase during a non-singular bounce. The analysis shows that the predicted primordial observables are consistent with the constraints reported by the Planck satellite.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
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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)
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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)
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Astronomy & Astrophysics
Duc Huy, Yi Wang, Juanyi Yang, Yuhang Zhu
Summary: This article introduces two new numerical methods for solving the difficulties in numerical calculations in quantum field theory, and compares their performance with existing methods.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
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Eemeli Tomberg, Hardi Veermae
Summary: Plateau inflation is an experimentally consistent framework where inflation scale remains relatively low. Tachyonic preheating occurs when the oscillating inflaton repeatedly re-enters the plateau after inflation. The analysis shows that in scenarios supporting tachyonic preheating, the inflaton fragments in a fraction of an e-fold with a small scalar-to-tensor ratio.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
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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)
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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)
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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)
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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)
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Astronomy & Astrophysics
Sourav Bhattacharya, Nitin Joshi
Summary: This paper investigates a massless, minimally coupled quantum scalar field theory with an asymmetric self interaction in the inflationary de Sitter spacetime. The results obtained using quantum mechanical methods and stochastic methods show similar qualitative behavior but differ numerically, and the reasons for this quantitative mismatch are discussed.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
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Astronomy & Astrophysics
Beatriz Elizaga Navascues, Guillermo A. Mena Marugan
Summary: This work analyzes the main differences between classical inflationary effects of a fast-roll regime and imprints of hybrid Loop Quantum Cosmology (LQC) on the primordial power spectrum, showing that the effects in LQC lead to a larger mode scale compared to classical relativistic cosmology.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
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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)
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Astronomy & Astrophysics
Harry Goodhew
Summary: This paper proves that the wavefunction coefficients are rational based on a set of assumptions, and generalizes the manifestly local test to higher dimensions. This greatly reduces the allowed space of functions that wavefunction coefficients can take in both the Effective Field Theory of Inflation and Pure Gravity models, and is thus a key ingredient in the Cosmological Bootstrap program.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
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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)
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Astronomy & Astrophysics
Zachary Kenton, David J. Mulryne
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(2016)
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Astronomy & Astrophysics
Lucia Fonseca de la Bella, Donough Regan, David Seery, Shaun Hotchkiss
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(2017)
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Astronomy & Astrophysics
Joyce Byun, Alexander Eggemeier, Donough Regan, David Seery, Robert E. Smith
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(2017)
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Astronomy & Astrophysics
Pedro Carrilho, David Mulryne, John Ronayne, Tommi Tenkanen
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(2018)
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Astronomy & Astrophysics
John W. Ronayne, David J. Mulryne
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2018)
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Sean Butchers, David Seery
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2018)
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Astronomy & Astrophysics
Lucia Fonseca de la Bella, Donough Regan, David Seery, David Parkinson
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2020)
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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.
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Astronomy & Astrophysics
Pedro Carrilho, Karim A. Malik, David J. Mulryne
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Shailee Imrith, David J. Mulryne, Arttu Rajantie
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Shailee V. Imrith, David J. Mulryne, Arttu Rajantie
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Clare Burrage, David Parkinson, David Seery
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Alexander Leithes, Karim A. Malik, David J. Mulryne, Nelson J. Nunes