Article
Astronomy & Astrophysics
M. Yoshimura
Summary: We propose models that predict the presence of dark energy, cold dark matter, and slow-roll inflation simultaneously. The density of dark energy is found to be of order (a few meV )(4), and the mass of dark matter constituent is approximately 1 meV. These models incorporate a multiscalar tensor gravity with nontrivial conformal coupling to the Ricci scalar curvature in the Lagrangian density, and make use of the spatially homogeneous kinetic contribution of Nambu-Goldstone modes in a spontaneously broken multiscalar field sector to explain the amount of dark energy. The proposed theories are consistent with general relativity tests at small cosmological distances but differ from general relativity at cosmological scales.
Article
Mathematics
Genly Leon, Alfredo D. Millano, Andronikos Paliathanasis
Summary: In this study, we investigate the phase space of a scalar field theory obtained through minisuperspace deformation. We consider quintessence or phantom scalar fields in the action derived from minisuperspace deformation on the Einstein-Hilbert action. Our analysis utilizes a modified Poisson algebra with alpha-deformed Poisson brackets that are linked to the Moyal-Weyl star product. We discuss both early- and late-time attractors and reconstruct the cosmological evolution. Additionally, we demonstrate that the model can exhibit the lambda CDM model as a future attractor if we start with a massless scalar field without a cosmological constant term.
Article
Physics, Multidisciplinary
Andronikos Paliathanasis
Summary: We address the group classification problem for gravitational field equations within the context of brane-world cosmology, considering the presence of a bulk scalar field. By applying the Lie symmetry condition, we find that only the exponential potential exhibits Lie symmetries, and we derive exact solutions for the system using Lie invariants.
Article
Multidisciplinary Sciences
Sergei V. Chervon, Igor V. Fomin
Summary: This study examines scalar-torsion gravity theories with exact solutions based on a physical type of potential for cosmological inflationary models involving the non-minimal coupling of a scalar field and torsion. Different inflationary dynamics and corresponding scalar field parameters are analyzed. This approach allows for the consideration of various physical potentials and types of scalar-torsion gravity theories in the realization of two stages of accelerated expansion in the universe. The correspondence between the proposed inflationary models and observational constraints on cosmological perturbation parameters is also explored.
Article
Mathematics
Alfredo D. Millano, Genly Leon, Andronikos Paliathanasis
Summary: We perform a detailed study of the phase-space of the field equations of an Einstein-Gauss-Bonnet scalar field cosmology for a spatially flat Friedmann-Lemaitre-Robertson-Walker spacetime. We consider the exponential function for the scalar field potential and assume two cases for the coupling function of the scalar field with the Gauss-Bonnet term: the exponential function and the power-law function. By writing the field equations in dimensionless variables and studying the equilibrium points using normalized and compactified variables, we recover previous results and discover new asymptotic solutions. These couplings provide a rich cosmological phenomenology.
Article
Astronomy & Astrophysics
Masaru Shibata, Dina Traykova
Summary: We numerically study the scalar wave emission caused by nonspherical oscillation of neutron stars in a scalar-tensor theory of gravity with kinetic screening. We find that the monopole emission is always suppressed by the screening effect, regardless of the size of the screening radius. However, the quadrupole mode is only suppressed for a screening radius larger than the wavelength of scalar waves, but not for smaller values.
Article
Physics, Particles & Fields
Arushi Bodas, Soubhik Kumar, Raman Sundrum
Summary: Non-analyticity in co-moving momenta within the non-Gaussian bispectrum is a distinctive sign of on-shell particle production during inflation. A combination of dimension-5 derivative couplings and chemical potential form operator provides an exception to the usual exponential drop in non-analyticity at masses exceeding the inflationary Hubble scale. This mechanism allows for the direct detection of particles with masses potentially as high as 10^(15) GeV, within the sensitivity of upcoming experiments.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Physics, Multidisciplinary
Nisha Godani, Gauranga C. Samanta
Summary: The paper explores the modification of general relativity and the presence of extra matter for traversable wormhole solutions, particularly in the background of f(R, T) gravity influenced by scalar field and electric charge. It examines the energy conditions with both the scalar field and electric charge, compares the results, and studies the existence of photon spheres due to strong gravitational lensing, along with the formation of relativistic images.
Article
Astronomy & Astrophysics
Anish Agashe, Mustapha Ishak
Summary: The theory of macroscopic gravity provides a formalism to average the Einstein field equations from small scales to largest scales, and this work derives exact solutions under the assumptions of averaged geometry being plane or spherically symmetric, and the source being vacuum, dust, or perfect fluid. The specific cases of spherical symmetry are studied and solutions analogous to the Schwarzschild, Tolman VII, and Lemaitre-Tolman-Bondi solutions are derived, with comparison to the geodesic equations and curvature structure in general relativity.
Article
Astronomy & Astrophysics
Sukanta Panda, Abbas Altafhussain Tinwala, Archit Vidyarthi
Summary: We calculate the tree-level ultraviolet unitarity violation scales for scalar-R2 inflation models by introducing an additional R2|Φ|2 term. Due to specific constraints, we perform the calculations in the Einstein frame and distinguish between metric and Palatini formulations. Following recent works, we debunk the naive predictions for unitarity violations in Higgs' inflation models, and determine how to accurately estimate the behavior of scattering amplitudes in the UV limit.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Rafael Hernandez-Jimenez, Claudia Moreno
Summary: Starting with the Lagrangian formulation of General Relativity, this study investigates the production of spacetime waves caused by a geometric boundary term of a closed extended manifold. The research explores two scenarios, Cold Inflation and Warm Inflation, and finds that scalar modes oscillate within the horizon and become constant after crossing the horizon, while radiation reduces their amplitudes. The tensor sector exhibits irregular behavior due to abrupt growth as it crosses the horizon, making it difficult to observe.
PHYSICS OF THE DARK UNIVERSE
(2023)
Article
Physics, Particles & Fields
Wen-Yuan Ai, Marco Drewes, Drazen Glavan, Jan Hajer
Summary: The study investigates the damping effects on the oscillations of a scalar field condensate in a thermal medium caused by dissipative effects. Through multiple-scale perturbation theory, approximate analytical solutions valid for very long times are obtained, revealing power-law damping of oscillations due to non-linear effects. By approximating the non-local equation of motion with a Markovianized one, it is justified to use Markovian equations at leading order, showing that standard time-dependent perturbation theory is insufficient to describe the non-linear condensate evolution. The macroscopic evolution of the condensate is explained in terms of microphysical particle processes.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Astronomy & Astrophysics
F. C. E. Lima, A. Yu Petrov, C. A. S. Almeida
Summary: We developed a perturbative generation approach for scalar-vector theories to investigate possible topological vortex structures in generalized models, demonstrating the necessity of nonpolynomial dielectric permeability functions such as the logarithmic function. By constructing models with logarithmic dielectric permeability in (2 + 1)D, we explored the presence of topological vortex structures in a Maxwell model.
Article
Astronomy & Astrophysics
Francesco Pace, Noemi Frusciante
Summary: In this study, the phase-space analysis of Quintessence models with two potentials is presented. The models show new scaling solutions and attractor solutions, which are of interest for addressing the coincidence problem and cosmic acceleration.
Article
Physics, Particles & Fields
Oliver Gould
Summary: This study investigates the thermal phase transitions of a generic real scalar field without Z(2)-symmetry, exploring dimensional reduction and perturbative calculations to three-loop order, as well as lattice simulations. The reliability of perturbation theory decreases as the cubic coupling decreases relative to the quartic coupling, but the renormalisation group is shown to extend its validity. The research aims to offer a guide for similar calculations in other theories by making calculations as explicit as possible.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Physics, Particles & Fields
Clifford Cheung, Grant N. Remmen
JOURNAL OF HIGH ENERGY PHYSICS
(2020)
Article
Physics, Particles & Fields
Ning Bao, Aidan Chatwin-Davies, Grant N. Remmen
Summary: This study generalizes constructions for multipartite reflected entropy and devises a general algorithm for constructing multipartite entanglement wedge cross sections with varying party numbers. It shows how these methods can be used to derive novel inequalities constraining multipartite entanglement wedge cross sections.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Astronomy & Astrophysics
Grant N. Remmen
Summary: We investigate a special class of singular solutions for a self-gravitating perfect fluid in general relativity known as the singular isothermal sphere. These solutions possess a fixed mass-to-radius ratio like black holes, but do not have a horizon cloaking the curvature singularity at r = 0. Particularly, for w = 1, these solutions can be constructed from a homogeneous dilaton background and we study their perturbative and geodesic structures.
GENERAL RELATIVITY AND GRAVITATION
(2021)
Article
Physics, Multidisciplinary
Grant N. Remmen
Summary: The physical properties of scattering amplitudes are linked to the Riemann zeta function, with real masses corresponding to the Riemann hypothesis, locality of the amplitude relating to the meromorphicity of the zeta function, and universal coupling between massive and massless states reflecting the simplicity of zeros of the zeta function. Additionally, unitarity bounds from dispersion relations for the forward amplitude translate to the positivity of odd moments of the sequence of 1/mu(2)(n).
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Particles & Fields
Achilleas P. Porfyriadis, Grant N. Remmen
Summary: A novel structure in Einstein-Maxwell-dilaton gravity is uncovered, featuring an AdS(2) x S-2 solution with independent length scales controlled by dilaton coupling lambda. The perturbation problem for this solution is solved, revealing independently propagating towers of states composed of gravitons, photons, and dilatons, with associated effective potentials. The effective potentials describe modes obeying conformal quantum mechanics and provide crucial data for any future construction of a holographic dual to these AdS(2) x S-2 configurations.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Physics, Particles & Fields
Nima Arkani-Hamed, Yu-tin Huang, Jin-Yu Liu, Grant N. Remmen
Summary: This study explores the shift in charge-to-mass ratio for extremal black holes in the context of effective field theory, constrained by unitarity and causality. The results demonstrate that the change in Q/M ratio is directly proportional to the on-shell action shift, ensuring compliance with the Weak Gravity Conjecture.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Physics, Particles & Fields
Achilleas P. Porfyriadis, Grant N. Remmen
Summary: This study uncovers the symmetry of the linear Einstein equations near extremal horizons. It shows that under certain transformations, the equations of motion remain satisfied for perturbative solutions to the Einstein-Maxwell equations.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Physics, Particles & Fields
Juan Maldacena, Grant N. Remmen
Summary: This paper compares the Coon amplitude with the open string scattering amplitude for strings ending on a D-brane in AdS, and finds several common features in their spectrum and high-energy behavior. These similarities suggest the existence of a string background that can realize the Coon amplitude.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Physics, Particles & Fields
Grant N. Remmen, Nicholas L. Rodd
Summary: We have constructed new dispersive sum rules for the effective field theory of the standard model at mass dimension six. These rules encode information about the spin of UV states and have various phenomenological applications. Our conclusions depend on the absence of potential poles at infinity, and we discuss in detail where these poles are expected to appear.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Physics, Particles & Fields
Clifford Cheunga, Grant N. Remmen
Summary: In this paper, a novel multi-parameter family of four-point scattering amplitudes is derived, exhibiting polynomially bounded high-energy behavior and exchange of an infinite tower of high-spin modes. These amplitudes take an infinite-product form and contain free parameters allowing customization of the spin-dependence. All partial waves are computed and unitary regions of parameter space are identified.
JOURNAL OF HIGH ENERGY PHYSICS
(2023)
Article
Physics, Particles & Fields
Achilleas P. Porfyriadis, Grant N. Remmen
Summary: This study investigates static, spherically symmetric, magnetically charged solutions in four-dimensional Einstein-Maxwell-dilaton gravity. The authors construct a three-parameter family of objects characterized by their mass, charge, and dilaton flux, and analyze their near-extremal and near-horizon behavior, finding new warped geometries. The authors also compute the static s-wave linearized solutions in a particular limit and explore the relation between horizon perturbations and their nonlinear completions in the generalized family of spacetimes.
JOURNAL OF HIGH ENERGY PHYSICS
(2023)
Article
Physics, Particles & Fields
Xi Dong, Grant N. Remmen, Diandian Wang, Wayne W. Weng, Chih-Hung Wu
Summary: This paper studies the invariance of holographic entanglement entropy under bulk renormalization group (RG) flow in AdS/CFT. The authors specifically focus on tree-level RG flow and provide evidence that holographic entanglement entropy calculated in the UV theory agrees with that calculated in the IR theory. They also generalize the replica method for calculating holographic entanglement entropy to include matter fields with nonzero spin.
JOURNAL OF HIGH ENERGY PHYSICS
(2023)
Article
Astronomy & Astrophysics
Yu-tin Huang, Grant N. Remmen
Summary: An infinite class of new ultraviolet-complete four-graviton scattering amplitudes is constructed, which exhibit several important features, including reducing to Einstein gravity, vanishing at high energies, and exhibiting a triple-product structure. Additionally, the study reveals some interesting results regarding mass poles.
Article
Astronomy & Astrophysics
Grant N. Remmen, Nicholas L. Rodd
Summary: In this study, we place theoretical constraints on the leading deviations to four-fermion standard model interactions and develop new dispersion relations that yield either spin-dependent sum rules on dimension-six fermionic operators or information about the amplitude's behavior at large momentum. These relations serve as a bridge between new physics searches, providing definitive information about the UV and enabling a diagnosis of properties of emerging new physics.
Article
Astronomy & Astrophysics
Ning Bao, Jonathan Harper, Grant N. Remmen
Summary: In this study, a bulk wormhole geometry interpolating between horizons of differing size is defined and characteristics of the Hubeny-Rangamani-Takayanagi surface in these geometries are determined. This construction is dual to black hole mesostates, representing an intermediate coarse-graining of states between black hole microstates and the full black hole state. The distinguishability of these objects is analyzed using holographic Holevo information techniques, showing novel phase transition behavior for such systems.