Results 121 to 130 of about 1,530,241 (273)

Mimicking Symmetry‐Breaking Einstein Ring by Optical Lens

open access: yesAdvanced Photonics Research, Volume 6, Issue 6, June 2025.
This article uses an optical lens to emulate the gravitational lensing effect and observe the Einstein ring (ER) patterns. The symmetry‐breaking ER, i.e., Einstein cross, is observed utilizing a rotation‐symmetry‐breaking hemi‐ellipsoid lens. Deformed Einstein cross patterns induced by noncollinearly alignment of the light source–lens–observer are ...
Jun‐Liang Duan   +5 more
wiley   +1 more source

Tachyon field in loop cosmology

open access: yesPhysics Letters B, 2020
The evolutionary pictures of tachyon field in modified loop cosmology have been investigated. We present the dynamical behavior of the tachyon field associated with an exponential potential and find that the pre-inflation dynamics are very similar in ...
Kui Xiao
doaj  

Minisuperspace Examples of Quantization Using Canonical Variables of the Ashtekar Type: Structure and Solutions

open access: yes, 1995
The Ashtekar variables have been use to find a number of exact solutions in quantum gravity and quantum cosmology. We investigate the origin of these solutions in the context of a number of canonical transformations (both complex and real) of the basic ...
A. Ashtekar   +18 more
core   +1 more source

Asymptotic Expansions Relating to the Distribution of the Product of Correlated Normal Random Variables

open access: yesStudies in Applied Mathematics, Volume 154, Issue 6, June 2025.
ABSTRACT Asymptotic expansions are derived for the tail distribution of the product of two correlated normal random variables with nonzero means and arbitrary variances, and more generally the sum of independent copies of such random variables. Asymptotic approximations are also given for the quantile function.
Robert E. Gaunt, Zixin Ye
wiley   +1 more source

Equivalence of Models in Loop Quantum Cosmology and Group Field Theory

open access: yesUniverse, 2019
The paradigmatic models often used to highlight cosmological features of loop quantum gravity and group field theory are shown to be equivalent, in the sense that they are different realizations of the same model given by harmonic cosmology.
Bekir Baytaş   +2 more
doaj   +1 more source

A novel holographic quantum phase transition and butterfly velocity

open access: yesJournal of High Energy Physics, 2022
In this paper, we make a systematical and in-depth exploration on the phase structure and the behaviors of butterfly velocity in an Einstein-Maxwell-dilaton-axions (EMDA) model.
Guoyang Fu   +5 more
doaj   +1 more source

Detailed analysis of the predictions of loop quantum cosmology for the primordial power spectra [PDF]

open access: yes, 2015
We provide an exhaustive numerical exploration of the predictions of loop quantum cosmology (LQC) with a post-bounce phase of inflation for the primordial power spectrum of scalar and tensor perturbations.
I. Agulló, Noah A. Morris
semanticscholar   +1 more source

Singular Electromagnetics: From Phase Singularities to Optical Skyrmions and Beyond

open access: yesAdvanced Physics Research, Volume 4, Issue 5, May 2025.
Singular electromagnetics/optics studies multidimensional topological defects of electromagnetic fields (also known as optical singularities), including phase and polarization singularities, 3D singularities (e.g., optical skyrmions, merons, hopfions, knots, links, and Möbius strips), and even higher‐dimensional singularities.
Jie Yang   +3 more
wiley   +1 more source

Cosmology as a CFT1

open access: yesJournal of High Energy Physics, 2019
We show that the simplest FLRW cosmological system consisting in the homo- geneous and isotropic massless Einstein-Scalar system enjoys a hidden conformal symmetry under the 1D conformal group SL(2, ℝ) acting as Mobius transformations in proper time ...
Jibril Ben Achour, Etera R. Livine
doaj   +1 more source

Mimetic gravity: mimicking the dynamics of the primeval universe in the context of loop quantum cosmology

open access: yesEuropean Physical Journal C: Particles and Fields, 2019
Mimetic gravity can be described as a formulation capable of mimicking different evolutionary scenarios regarding the universe dynamics. Notwithstanding its initial aim of producing a similar evolution to the one expected from the dark components of the ...
Eunice Bezerra, Oswaldo D. Miranda
doaj   +1 more source

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