Article
Astronomy & Astrophysics
Philippe Brax, Andrei Lazanu
Summary: DHOST inflation models with deviations from a pure de Sitter background induced by an axion-like potential can result in large non-Gaussianities. We investigate the characteristics of non-Gaussianities in these models and compare them to the findings of the Planck experiment. The overlap between DHOST non-Gaussianities and the equilateral, orthogonal, and local templates can be arbitrarily small, but this does not rule out the possibility of DHOST models exhibiting large non-Gaussianities.
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
Alba Kalaja, P. Daniel Meerburg, Guilherme L. Pimentel, William R. Coulton
Summary: The study investigates the cosmic variance limit on constraining primordial non-Gaussianity for various theory-motivated shapes. It identifies that the scale-invariant N-point correlator's signal-to-noise does not scale as naively expected with the square root of observed modes due to factors such as blurring of the last scattering surface and behavior in squeezed and collapsed limits. Analytical estimates and numerical calculations confirm these findings, and the addition of polarization data enhances scaling for certain spectra.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Nicola Bartolo, Luca Caloni, Giorgio Orlando, Angelo Ricciardone
Summary: The paper investigates inflation within chiral scalar-tensor theories of gravity, extending by including parity-violating operators. The study analyzes the effects of parity-violation on primordial tensor non-Gaussianity.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Mehrdad Mirbabayi, Andrei Gruzinov
Summary: Sphaleron heating is proposed as a mechanism for warm inflation when the inflaton is coupled to pure Yang-Mills as an axion. The presence of heating introduces a friction coefficient gamma proportional to T-3 in the inflaton's equation of motion, as well as a thermal contribution to cosmological fluctuations. In the absence of knowledge about the inflaton potential, non-Gaussianity is the most promising approach for detecting the signatures of this model. By extending previous work, we compute the scalar three-point correlation function and identify distinct features in the squeezed and folded limits. As a detection strategy, we find that combining the equilateral template with a new template yields a high overlap with the shape of non-Gaussianity for 0.01 <= gamma/H <= 1000, with 0.7 < |f(NL)| < 50 in this range.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Hemza Azri, Isaac Bamwidhi, Salah Nasri
Summary: This paper explores two-field inflation in the context of purely affine gravity, introducing a covariant formulation that leads to a curved field space allowing for significant departure from purely metric gravity. By allowing specific noncanonical field kinetic terms, the curved field manifold can be flattened, simplifying inflationary dynamics and enabling new predictions.
Article
Physics, Multidisciplinary
Timo J. Doerries, Ralf Metzler, Aleksei Chechkin
Summary: This article examines the transport of diffusive particles switching between mobile and immobile states with finite rates. The study focuses on the impact of advection on density functions and mean squared displacements (MSDs). Significant anomalous diffusion with cubic scaling in time of the MSD is found at intermediate time scales for high Peclet numbers. This cubic scaling is present for both short and long mean residence times in the immobile state. The study also reveals the newly observed phenomenon of advection-induced subdiffusion for immobilized tracers in the presence of high Peclet numbers. Additionally, the effective advection velocity is reduced in the long-time limit, while the MSD is enhanced by advection. The physical mechanisms behind the emergence of non-Gaussian density functions and the characteristics of the MSD are explored.
NEW JOURNAL OF PHYSICS
(2023)
Article
Astronomy & Astrophysics
Ariel G. Sanchez, Andres N. Ruiz, Jenny Gonzalez Jara, Nelson D. Padilla
Summary: We present a new approach to describe the statistics of the non-linear matter density field by exploiting a degeneracy in the impact of different cosmological parameters. By classifying the parameters into shape and evolution parameters, we are able to map the time evolution of the matter power spectrum between models with identical shape parameters. Our N-body simulations show that this mapping relation can accurately describe the non-linear power spectrum, halo mass function, and full density field.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Maria Mylova, Marianthi Moschou, Niayesh Afshordi, Joao Magueijo
Summary: This paper introduces a thermal bimetric model and explores its non-Gaussian features, providing precise predictions based on the characteristics of the model. These results are of great significance for future cosmological surveys.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Lurdes Ondaro-Mallea, Raul E. Angulo, Matteo Zennaro, Sergio Contreras, Giovanni Arico
Summary: In this study, the authors investigate the dependence of halo mass function on growth history and power spectrum shape using specially designed cosmological simulations. They propose a parameterization with explicit dependence on linear growth rate and power spectrum shape, and show that it accurately captures the mass function of haloes over a wide range of cosmologies. They also demonstrate the improved accuracy of cosmology-rescaling methods using this tool.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Takahiko Matsubara, Satoshi Kuriki
Summary: Minkowski functionals are statistical quantities used to quantify the morphology of random fields, widely applied in cosmology and image processing. Non-Gaussianity is crucial for these analyses, and analytic formulas for corrections have been derived. This study generalizes and extends previous works on non-Gaussianity corrections for Minkowski functionals in general dimensional spaces.
Article
Astronomy & Astrophysics
Satoshi Iso, Takato Mori, Katsuta Sakai
Summary: This paper extends a previous study on the entanglement entropy of a half space in interacting field theories, introducing a novel calculation method and identifying two specific contributions to the entanglement entropy. Further investigation in more general field theories suggests that non-Gaussian contributions from vertices can be understood as renormalized correlation functions of composite operators.
Article
Astronomy & Astrophysics
Sarvesh Kumar Yadav, Rajib Saha
Summary: This paper examines the validity of the assumption that the temperature field of the Cosmic Microwave Background (CMB) is consistent with a Gaussian random field. A new model-independent method using ordered and non-parametric statistics is proposed and applied to test the uniformity and independence of the CMB spherical harmonic phases (SHP). The results show that there are non-uniform and correlated SHP in the cleaned CMB maps, indicating the presence of non-Gaussian signals.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Physics, Multidisciplinary
Jiyong Park
Summary: The study introduces a method for deriving a lower bound for a non-Gaussianity measure based on quantum relative entropy and demonstrates its effectiveness compared to previous methods. Additionally, the method is extended to measurements of multi-mode quantum states and finds application in non-Gaussian entanglement detection.
Article
Astronomy & Astrophysics
Matthew W. Davies, Pedro Carrilho, David J. Mulryne
Summary: In this study, we work within an idealized framework to match a series of evolution phases defined by the second slow-roll parameter eta. We calculate the reduced bispectrum, f(NL), for inflation models with a significant peak in their primordial power spectra. Our findings show that f(NL) remains relatively constant over the scales where the peak is located, and we provide an analytic approximation for this value. Additionally, we identify the conditions under which f(NL) is large enough to have a significant impact on the production of primordial black holes (PBHs) and scalar induced gravitational waves (SIGWs). The analytic formulas for the gradient of the rise and fall in the power spectrum, along with these findings, offer a toolkit for designing or quickly analyzing inflationary models that generate PBHs and SIGWs.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
