Article
Astronomy & Astrophysics
Raihaneh Moti
Summary: In the absence of an exact development of the cosmological models based on the Mashhoon nonlocal gravity, the Newtonian regime clarifies some aspects of it. To improve this model, semi-Post-Newtonian considerations may be useful. One important feature to consider is the formation of horizons, which can be understood as a consequence of the finite interaction velocity. In this context, it is found that the density of effective dark matter would increase while the density of Baryonic matter decreases during the deep matter-dominated era.
PHYSICS OF THE DARK UNIVERSE
(2023)
Article
Astronomy & Astrophysics
Aritra Banerjee, Aditya Mehra
Summary: This paper introduces a Galilean cousin of the ModMax theory and demonstrates its invariance under Galilean conformal symmetries. By discussing the construction of Galilean electromagnetic invariants, it shows that the classical structure of the theory is invariant under the action of Galilean conformal algebra.
Article
Physics, Multidisciplinary
Miguel Gallego, Borivoje Dakic
Summary: It is commonly believed that coarse graining of quantum correlations leads to classical correlations in the macroscopic limit. However, this letter finds that in the non-IID scenario, the Hilbert space structure of quantum theory can be preserved in the macroscopic limit, leading to a violation of macroscopic locality through Bell inequality.
PHYSICAL REVIEW LETTERS
(2021)
Article
Astronomy & Astrophysics
Niels Fardeau, Thomas Buchert, Fosca Al Roumi, Fereshteh Felegary
Summary: This research reviews the study of structure formation in the Universe and extends the Eulerian and Lagrangian approaches to include velocity dispersion. By comparing numerical results of different models, it is found that linearized Lagrangian solutions outperform models based on Burgers' equation in the multistream regime.
Article
Physics, Mathematical
Hans Knuepfer, Wenhui Shi
Summary: The seminal results of Bourgain et al. and Davila show that the classical perimeter can be approximated by a family of nonlocal perimeter functionals. A second order expansion for the nonlocal perimeter functional is considered, which is also relevant in a variational model for thin ferromagnetic films. The Gamma-limit of these functionals as epsilon approaches 0 is derived, and existence of minimizers with prescribed volume fraction is shown. For small volume fraction, the unique minimizer of the limit energy is given by the ball. The analysis is based on the exploitation of the associated symmetrized autocorrelation function.
COMMUNICATIONS IN MATHEMATICAL PHYSICS
(2023)
Article
Astronomy & Astrophysics
P. C. Lalremruati, Sanjeev Kalita
Summary: This study investigates the breaking points of general relativity (GR) through the estimation of pericenter shift of stellar orbits near the Galactic center black hole. The findings suggest the existence of breaking points for higher scalaron coupling in GR. Additionally, the allowed ranges of the five-dimensional Planck mass are estimated using a power-law potential and constraints from parameterized post-Newtonian parameters. The study also presents the potential for astrometric measurements to constrain this parameter.
ASTROPHYSICAL JOURNAL
(2022)
Article
Mathematics, Applied
Mengna Yang, Shangyuan Zhang, Yufeng Nie
Summary: In this paper, a linear bond-based peridynamic nonlocal evolution problem with the nonlocal viscoelastic damping term is considered. The existence, uniqueness, and continuous dependence upon datum of a weak solution are proven using Galerkin methods. The regularity results of weak solutions in time are established along with the energy inequality. Additionally, the limit behavior of the weak solution as delta -> 0 is briefly analyzed, showing that its limit function solves the corresponding classical local evolution problem exactly. Under stronger regularity conditions for solutions, the solution of the nonlocal evolution problem strongly converges to the solution of the corresponding classical local problem only in the interior of domain omega.
JOURNAL OF MATHEMATICAL ANALYSIS AND APPLICATIONS
(2023)
Article
Astronomy & Astrophysics
Donato Bini, Thibault Damour, Andrea Geralico, Stefano Laporta, Pierpaolo Mastrolia
Summary: A recently introduced approach to classical gravitational dynamics of binary systems involves intricate integrals that have resisted analytical evaluation. By utilizing computing techniques for multiloop Feynman integrals, the authors demonstrate how to analytically compute all integrals related to nonlocal-in-time contributions to the classical scattering angle at high accuracy levels.
Article
Physics, Multidisciplinary
Roberto Casadio, Octavian Micu, Jonas Mureika
Summary: This study investigates the possible existence of a Newtonian regime of gravity in 1 + 1 dimensions, examining metrics in both the Kerr-Schild and conformal forms. In the Kerr-Schild case, the metric provides an exact solution to the Poisson equation in flat space, but the weak-field limit and non-relativistic regime of geodesic motion are not trivial. By utilizing harmonic coordinates, the metric is shown to be conformally flat and a weak-field expansion becomes straightforward. However, the analysis of the non-relativistic regime of geodesic motion remains complex, and the weak-field potential only approximately satisfies the flat space Poisson equation.
Article
Astronomy & Astrophysics
Martha Constantinou, Haralambos Panagopoulos
Summary: In this paper, an improved regularization-independent (RI)-type prescription is presented for the nonperturbative renormalization of gauge-invariant nonlocal operators. This method involves subtracting finite lattice spacing effects calculated in lattice perturbation theory to improve the nonperturbative vertex function. The approach is versatile, applicable to various fermion and gluon actions, and different types of nonlocal operators.
Article
Astronomy & Astrophysics
Javad Tabatabaei, Abdolali Banihashemi, Shant Baghram, Bahram Mashhoon
Summary: Within the framework of local limit of nonlocal gravity, we investigate a class of spatially homogeneous but anisotropic cosmological models, exploring the modified field equations and their solutions, as well as the contribution of the susceptibility function to cosmic acceleration. The implications for observational cosmology are briefly discussed.
Article
Astronomy & Astrophysics
Anish Ghoshal, Florian Nortier
Summary: This article discusses the Coleman bounce in weakly nonlocal theories, which are inspired by string field theory. The study finds that the nonlocal scale M in the theory suppresses the vacuum tunneling rate from false to true vacuum and this suppression is significant only around the wall of the nucleated bubble.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Physics, Multidisciplinary
Jan Harms, Luca Naticchioni, Enrico Calloni, Rosario De Rosa, Fulvio Ricci, Domenico D'Urso
Summary: The Einstein Telescope is a proposed third-generation underground observatory for gravitational wave detection. It aims to have increased sensitivity and extend the observation band to lower frequencies. However, the sensitivity of the telescope is limited by environmental factors, especially seismic activity, which generates Newtonian noise. Accurate models of this noise are crucial to assess the feasibility of potential sites for the telescope and to identify areas for improvement.
EUROPEAN PHYSICAL JOURNAL PLUS
(2022)
Article
Physics, Particles & Fields
A. Capolupo, G. Lambiase, A. Stabile, An. Stabile
Summary: This study examines the virial theorem in the context of scalar tensor fourth order gravity in the Newtonian limit. It demonstrates that a specific class of this theory is not suitable for explaining the large fraction of dark matter needed to account for the flatness of galaxies' rotation curves observed experimentally.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Statistics & Probability
Simon C. Harris, Emma Horton, Andreas E. Kyprtanou, Minmin Wang
Summary: This article considers the classical Yaglom limit theorem for a branching Markov process with nonlocal branching mechanism. It shows that under critical mean semigroup, there exists a constant c(f) such that the distribution of a certain expression converges to an exponential random variable. The article also proves that the probability of survival decays inversely proportionally to time. The importance of this article lies in its precise results for the scaled asymptotics for the kth martingale moments of X and its application in neutron transport.
ANNALS OF PROBABILITY
(2022)
Article
Physics, Particles & Fields
Sebastian Bahamonde, Viktor Gakis, Stella Kiorpelidi, Tomi Koivisto, Jackson Levi Said, Emmanuel N. Saridakis
Summary: This study explores cosmological perturbations in a new framework of gravity, including gravitational propagation equations, vector perturbation stability conditions, and scalar perturbations. The effective gravitational constant is derived, revealing an interesting branching behavior dependent on specific gravitational models being probed. A discussion is provided on the relation of these results with other gravitational theories.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Astronomy & Astrophysics
Jose Beltran Jimenez, Tomi S. Koivisto
Summary: In this paper, a general framework for constructing the Einstein frame within non-linear extensions of teleparallel equivalents of General Relativity is provided. It is shown that all non-linear extensions share the same quadratic action around Minkowski backgrounds. Additionally, the conformal mode can be absorbed into a Weyl rescaling of the metric at this order, disappearing from the linear spectrum.
Editorial Material
Physics, Mathematical
Christian Pfeifer, Martin Krssak, Tomi Koivisto, Sebastian Bahamonde, Manuel Hohmann, Laur Jarv, Margus Saal
Summary: The paper studies spherical symmetry in a modified teleparallel theory of gravity based on an arbitrary function of five possible scalars constructed from the irreducible parts of torsion. The theory is a generalization of the New General Relativity theory. The study analytically solves the corresponding field equations for conformal Teleparallel gravity and perturbatively around Schwarzschild geometry for the general perturbative theory around GR, ultimately computing phenomenological effects from the perturbed solutions.
INTERNATIONAL JOURNAL OF GEOMETRIC METHODS IN MODERN PHYSICS
(2021)
Article
Physics, Particles & Fields
Gert Hutsi, Tomi Koivisto, Martti Raidal, Ville Vaskonen, Hardi Veermae
Summary: The study shows that the mass growth of compact objects described by the Thakurta metric cannot be supported by radiation, primordial black holes, or particle dark matter. This means that existing constraints on the abundance of primordial black holes from the LIGO-Virgo and CMB measurements remain valid.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Multidisciplinary Sciences
Priidik Gallagher, Tomi Koivisto
Summary: The essay demonstrates that the two main issues of the standard cosmological model arise as integration constants in a careful derivation from first principles in a Lorentz gauge theory. The dark sector of the universe may simply reflect a spontaneous symmetry breaking necessary for the existence of spacetime and an observer within it.
Article
Physics, Mathematical
Jose Beltran Jimenez, Tomi S. Koivisto
Summary: This paper focuses on the subtleties involved in the applications of the coincident gauge in the context of the simplest, integrable, flat, torsion-free, and symmetric teleparallel affine connection.
INTERNATIONAL JOURNAL OF GEOMETRIC METHODS IN MODERN PHYSICS
(2022)
Article
Physics, Mathematical
Tomi Koivisto
Summary: This passage discusses the definition and understanding of concepts such as time, energy, entropy, and information, built upon the foundation of relativistic gravity. The author attempts to explain the fundamental principles behind this progress, highlighting the universal definition of energy and unearthing them from Einstein's theory and Noether's theorems, which were previously misconstrued for a century.
INTERNATIONAL JOURNAL OF GEOMETRIC METHODS IN MODERN PHYSICS
(2022)
Article
Astronomy & Astrophysics
Jose Beltran Jimenez, Tomi S. Koivisto
Summary: This essay delves into the framework of normed division algebras as a suitable arena for accommodating the standard model of elementary particles and explores applications to cosmology, particularly focusing on the interesting non-trivial realizations of the cosmological principle with an interplay between the symmetry groups of quaternions and octonions and their potential observational signatures in gravitational waves astronomy.
Article
Astronomy & Astrophysics
Tomi Koivisto, Tom Zlosnik
Summary: In special-relativistic physics, the fixed metric tensor of spacetime is proposed to be promoted to a dynamical field in order to develop a gravitational theory. Another description of special-relativistic physics suggests the inclusion of scalar fields that can dynamically take the form of inertial coordinates, without a fixed spacetime geometry. This alternative approach to gravity introduces gauge fields to promote the invariance of actions under global or local transformations, leading to gravitational theories with similarities and differences to general relativity. Among these theories, the one based on local Lorentz symmetry extends general relativity and allows for the introduction of a standard of time into the dynamics of the gravitational field, even with a non-zero curvature.
Article
Astronomy & Astrophysics
Tomi S. Koivisto
Summary: Symmetric teleparallel gravity is proved to be integrable with the existence of boundaries, when constraints are consistently implemented in the covariant phase space formalism.
Article
Astronomy & Astrophysics
Priidik Gallagher, Tomi Koivisto, Luca Marzola
Summary: The standard description of particles and fundamental interactions relies on a regular metric background. However, in a pregeometric phase where the metric is degenerate, the conventional forms of scalar and Yang-Mills actions are no longer valid. Instead, a first order formalism is suggested where the metric can emerge from more fundamental constituents. By exploring different realizations of this formalism, it is found that a fundamental vector or spinor substructure can result in continuum magnetization and polarization. This effect bears resemblance to the description of the cosmological dark sector in self-dual gravity, opening up new paths towards unification.
Article
Astronomy & Astrophysics
Jose Beltran Jimenez, Tomi S. Koivisto
Summary: The Noether currents are derived in a generic metric-affine theory of gravity, and the holographic nature of the gravitational entropy and energy-momentum is clarified. The main result is the verification of the canonical resolution to the energy-momentum problem in the Noether formalism.
Article
Astronomy & Astrophysics
Tomi S. Koivisto, Luxi Zheng
Summary: This article presents a new de Sitter gauge theory of gravity that allows for the consistent evolution of the fundamental distance limit e, offering a novel nonsingular extension of cosmology.
Article
Astronomy & Astrophysics
Tomi Koivisto, Manuel Hohmann, Luca Marzola
Summary: This text deduces a theory of gravity from the axioms of the premetric program, emphasizing the conservation of energy and momenta, the equivalence of gravitation and inertia, and the framework of purified gravity. By making the constitutive relation compatible with an action principle, the theory of coincident general relativity is uniquely fixed. The premetric formalism of purified gravity has a direct analogy with massive electromagnetism, with the metric emerging as a Stueckelberg field and the graviton as a Goldstone boson of the broken symmetry.
Article
Astronomy & Astrophysics
Jose Beltran Jimenez, Alexey Golovnev, Tomi Koivisto, Hardi Veermae
Summary: This note examines the full set of solutions of f(T) gravity with the Minkowski metric, revealing a new mode at the fourth order in perturbations around the trivial tetrad solution. The presence of this new mode indicates a strong coupling problem that goes beyond the Minkowski background and suggests the ambiguous nature of cosmological solutions.
