Results 41 to 50 of about 50,468 (222)

Complex Riemannian Spacetime and Singularity-Free Black Holes and Cosmology

Axioms
An approach is presented to address singularities in general relativity using a complex Riemannian spacetime extension. We demonstrate how this method can be applied to both black hole and cosmological singularities, specifically focusing on the ...
John W. Moffat
doaj   +1 more source

Non-metricity signatures on the Higgs boson signal strengths at the LHC

Journal of High Energy Physics, 2022
In this work we study the high-energy Higgs boson phenomenology associated to the non-metricity scale Λ Q at the LHC. Non-metricity is present in more generic non-Riemannian geometries describing gravity beyond General Relativity and exhibits nice ...
Victor Ilisie
doaj   +1 more source

Generalized Rest Mass and Dirac’s Monopole in 5D Theory and Cosmology

Universe, 2021
It is shown that the 5D geodetic equations and 5D Ricci identities give us a way to create a new viewpoint on some problems of modern physics, astrophysics, and cosmology.
Boris G. Aliyev
doaj   +1 more source

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

, 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, A. Lafiti, A. Taub, C. Misner, H. Kodama, H. Kodama, I. E. Segal, J. F. Barbero, J. Fernando Barbero, J. Hartle, K. Kuchař, M. Ryan, Michael P. Ryan, O. Obregon, P. D'Eath, R. Graham, V. Bargmann, V. Belinskii, V. Moncrief   +18 more
core   +1 more source

Group Field Theory and Its Cosmology in a Matter Reference Frame

Universe, 2018
While the equations of general relativity take the same form in any coordinate system, choosing a suitable set of coordinates is essential in any practical application.
Steffen Gielen
doaj   +1 more source

Effective actions for loop quantum cosmology in fourth-order gravity

European Physical Journal C: Particles and Fields, 2021
Loop quantum cosmology (LQC) is a theory which renders the Big Bang initial singularity into a quantum bounce, by means of short-range repulsive quantum effects at the Planck scale.
Marcello Miranda, Daniele Vernieri, Salvatore Capozziello, Francisco S. N. Lobo   +3 more
doaj   +1 more source

A simple parity violating model in the symmetric teleparallel gravity and its cosmological perturbations

Physics Letters B, 2022
Parity violating models based on the symmetric teleparallel gravity have been considered in the literature, but their applications in cosmology and especially the features in cosmological perturbations have not been fully explored.
Mingzhe Li, Dehao Zhao
doaj   +1 more source

Simple quantum cosmology: Vacuum energy and initial state

, 2005
A static non-singular 10-dimensional closed Friedmann universe of Planck size, filled with a perfect fluid with an equation of state with w = -2/3, can arise spontaneously by a quantum fluctuation from nothing in 11-dimensional spacetime.
D. Spergel, D. Youm, E. Elbaz, M. Novello, M. Tegmark, S. Alexander, S. Eidelman, T. R. Mongan, T.R. Mongan   +8 more
core   +2 more sources

Shedding light on gravity: Black hole shadows and lensing signatures in Lorentz gauge theory

Nuclear Physics B
Recent advances, including gravitational wave detections and imaging of black hole shadows, have strongly validated general relativity. Nevertheless, ongoing cosmological observations suggest potential limitations of general relativity, spurring interest
Ali Övgün, Mohsen Fathi
doaj   +1 more source

Cosmological perturbations in a class of fully covariant modified theories: application to models with the same background as standard LQC

European Physical Journal C: Particles and Fields, 2018
Bouncing cosmologies are obtained by adding to the Einstein–Hilbert action a term of the form $$\sqrt{-\,g}f(\chi )$$ -gf(χ) , with $$\chi $$ χ a scalar depending on the Hubble parameter only, not on its derivatives, and which is here shown to arise from
Jaume de Haro, Llibert Aresté Saló, Emilio Elizalde   +2 more
doaj   +1 more source