Article
Astronomy & Astrophysics
Justin Khoury
Summary: This paper introduces a new measure for eternal inflation, focusing on efficiently accessed vacua under time evolution. The proposed measure is independent of initial conditions and can make concrete and testable predictions.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Georgios Fanaras, Alexander Vilenkin
Summary: In this study, we investigate the quantum cosmology and eternal inflation beyond the slow roll regime in light of the recent swampland conjectures. We consider a closed universe model with a scalar field phi and use the tunneling approach to quantum cosmology. Our findings reveal that the dominant nucleation channel for the universe is tunneling to a homogeneous, spherical de Sitter space when m < 2H, and to an inhomogeneous closed universe with a domain wall wrapped around its equator for larger values of m/H. The quantum state of the field phi in the nucleated universe is determined by solving the Wheeler-DeWitt equation with tunneling boundary conditions.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Min-Seok Seo
Summary: This paper discusses the influence of quantum fluctuations and density fluctuations on black hole production in inflation. It proposes the equivalence between the no eternal inflation condition and the condition that radiation density fluctuations are not sufficient to produce black holes. It also highlights that the information paradox does not arise when the radiation emitted by the horizon does not produce black holes.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Oliver Hahn, Cornelius Rampf, Cora Uhlemann
Summary: A novel approach to generating higher order initial conditions for cosmological simulations is presented, addressing issues in two-fluid simulations and demonstrating comparable improvements to single-fluid simulations. Rigorous development of the perturbation theory underlying the method is discussed in a companion paper.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Review
Astronomy & Astrophysics
Valerio Bozza
Summary: This paper reviews the evolution of perturbations in bouncing cosmologies and discusses significant attempts to reconcile predicted spectra with observations. Bouncing cosmologies, particularly the pre-Big Bang scenario, are viable alternatives to inflation that can help address current theoretical and observational tensions.
Article
Astronomy & Astrophysics
Willem Elbers, Carlos S. Frenk, Adrian Jenkins, Baojiu Li, Silvia Pascoli
Summary: The discovery of neutrinos having mass has significant implications for cosmology, particularly in suppressing the growth of small-scale cosmic structures. This paper demonstrates that the effects of neutrinos can be accounted for in higher order Lagrangian perturbation theory, allowing for the use of higher order initial conditions in simulations. The study shows that increasing the order substantially improves the accuracy of simulations.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Shogo Masaki, Takahiro Nishimichi, Masahiro Takada
Summary: This paper investigates the effects of pre-initial conditions on cosmological N-body simulations, revealing artificial features in grid pre-IC simulations while glass pre-IC simulations are more stable and accurate. The study shows that in the high redshift range, the coupling between large-scale tidal field and matter clustering is enhanced, highlighting the significance of tidal field on structure formation, especially during the epoch of reionization.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Michael Michaux, Oliver Hahn, Cornelius Rampf, Raul E. Angulo
Summary: The study suggests that using third-order Lagrangian perturbation theory (3LPT) for initial conditions can significantly suppress truncation errors, allowing for accurate initialization of simulations at later times.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Eleni-Alexandra Kontou, Ken D. Olum
Summary: This paper demonstrates that eternal inflation is possible even when energy conditions are obeyed. While energy conditions restrict the evolution of any single quantum state, the process of eternal inflation involves selecting a subsector of the previous state, avoiding violation of the conditions.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Physics, Particles & Fields
Anders Tranberg, Gerhard Ungersback
Summary: Classical-statistical lattice simulations are a useful approximation for out-of-equilibrium quantum field theory, but only for systems with large occupation numbers and phenomena that are not intrinsically quantum mechanical. In certain cases, initializing these simulations with quantum-like zero-point fluctuations can be appropriate. However, the reported numerical agreement between classical-statistical simulations and quantum bubble nucleation rates in 1+1 dimensions is coincidental and dependent on parameters and lattice cut-off, disappearing when the number of space dimensions increases to 2+1.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Astronomy & Astrophysics
Shao-Jiang Wang, Zi-Yan Yuwen
Summary: This paper proposes an iteration method that takes into account the variation of sound velocity across the bubble wall for a general and realistic equation of state (EoS) beyond the simple bag model and v-model. The study finds a suppression effect for the efficiency factor of bulk fluid motions, though it may be negligible for strong phase transitions.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Justin Khoury, Sam S. C. Wong
Summary: This research explores the possibility of our existence in the early stages of the universe, proposing an early-time measure for vacuum systems that favors short-lived vacua, funneled regions, and small positive vacuum energy. It also draws an analogy to protein folding energy landscapes.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Pedro Carrilho, Karim A. Malik
Summary: This paper investigates the relationship between the bispectra of the cosmic microwave background and isocurvature modes, as well as the ability of current and future CMB experiments to constrain these modes. Results show that a detectable bispectrum signal can be produced when the compensated isocurvature mode has significant correlation with the adiabatic mode.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
David Camarena, Valerio Marra, Ziad Sakr, Chris Clarkson
Summary: A program was pursued to test the Copernican principle by confronting observations with inhomogeneous extensions of the FLRW metric, which found that the extra inhomogeneity can be tightly constrained by current data without weakening the constraints on cosmological parameters. This positive result suggests that present and future data can be meaningfully analyzed within the framework of inhomogeneous cosmology.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Micol Benetti, Salvatore Capozziello, Gaetano Lambiase
Summary: Researchers conducted a detailed study on viable f(T) teleparallel cosmological models, including power law, exponential, and square-root exponential, analyzing their evolution at different scales. Through a combination of measurements, they obtained narrow constraints on the free parameters of these models, indicating a preference for extended gravity models in observations.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Physics, Particles & Fields
Sebastian Garcia-Saenz, Ermis Mitsou, Alberto Nicolis
JOURNAL OF HIGH ENERGY PHYSICS
(2018)
Article
Physics, Particles & Fields
G. Giribet, C. Hull, M. Kleban, M. Porrati, E. Rabinovici
JOURNAL OF HIGH ENERGY PHYSICS
(2018)
Article
Astronomy & Astrophysics
Valentino F. Foit, Matthew Kleban
CLASSICAL AND QUANTUM GRAVITY
(2019)
Article
Physics, Multidisciplinary
Angelo Esposito, Rafael Krichevsky, Alberto Nicolis
PHYSICAL REVIEW LETTERS
(2019)
Article
Astronomy & Astrophysics
Vitor Cardoso, Valentino F. Foit, Matthew Kleban
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2019)
Article
Physics, Particles & Fields
Lasma Alberte, Alberto Nicolis
JOURNAL OF HIGH ENERGY PHYSICS
(2020)
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
Physics, Particles & Fields
Ioanna Kourkoulou, Alberto Nicolis, Guanhao Sun
Summary: The article discusses a technically similar problem in a system called framid, where the stress-energy tensor has a Lorentz-invariant expectation value on the ground state without symmetry-based selection rules enforcing it. The Lorentz invariance of the expectation value is verified through explicit one-loop computations, which depend on highly nontrivial cancellations to yield the expected results.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Astronomy & Astrophysics
Alberto Nicolis, Federico Piazza, Kenza Zeghari
Summary: This paper revisits rotating cosmologies within the framework of mini-superspace, emphasizing the symmetries and conservation laws. The physical rotation of solid-driven cosmologies is characterized by a conserved angular momentum. The results confirm previous findings regarding the slow decay of anisotropies in solid inflation.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Physics, Particles & Fields
Austin Joyce, Alberto Nicolis, Alessandro Podo, Luca Santoni
Summary: The text discusses the subtleties of renormalization that arise when deriving a low-energy effective action by integrating out heavy fields of a more complete theory. It provides a concrete example of applying this method to derive the U(1) Goldstone low-energy effective theory and the one-loop equation of state for the superfluid phase of (complex) phi(4). Additionally, it analyzes a renormalizable scalar SO(N) theory at finite chemical potential, demonstrating the absence of the original SO(N) symmetry in the effective theory for the gapless Goldstone.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Physics, Mathematical
Federico Camia, Valentino F. Foit, Alberto Gandolfi, Matthew Kleban
Summary: The Brownian loop soup is a conformally invariant statistical ensemble of random loops in two dimensions. Recent progress has led to an analytic form for the four-point function of a class of scalar conformal primary layering vertex operators O-beta. This paper introduces the edge counting field epsilon(z) and rigorously proves the well-definedness and behavior of its n-point functions.
COMMUNICATIONS IN MATHEMATICAL PHYSICS
(2023)
Article
Physics, Particles & Fields
Angelo Esposito, Rafael Krichevsky, Alberto Nicolis
JOURNAL OF HIGH ENERGY PHYSICS
(2020)
Article
Materials Science, Multidisciplinary
Thomas C. Bachlechner, Matthew Kleban
Article
Astronomy & Astrophysics
Thomas C. Bachlechner, Kate Eckerle, Oliver Janssen, Matthew Kleban
Article
Materials Science, Multidisciplinary
Alberto Nicolis, Riccardo Penco