Results 41 to 50 of about 42,432 (292)

The non-minimal coupling constant and the primordial de Sitter state

European Physical Journal C: Particles and Fields, 2020
Dynamical systems methods are used to investigate dynamics of a flat Friedmann–Robertson–Walker cosmological model with the non-minimally coupled scalar field and a potential function.
Orest Hrycyna
doaj   +1 more source

An Effective Sign Switching Dark Energy: Lotka–Volterra Model of Two Interacting Fluids

Universe, 2023
One of the recent attempts to address the Hubble and S8 tensions is to consider that the Universe started out not as a de Sitter-like spacetime, but rather anti-de Sitter-like. That is, the Universe underwent an “AdS-to-dS” transition at some point.
Yen Chin Ong
doaj   +1 more source

Primordial Dark Energy from a Condensate of Spinors in a 5D Vacuum

Advances in High Energy Physics, 2013
We explore the possibility that the expansion of the universe can be driven by a condensate of spinors which are free of interactions in a 5D relativistic vacuum defined in an extended de Sitter spacetime which is Riemann flat.
Pablo Alejandro Sánchez, Mauricio Bellini   +1 more
doaj   +1 more source

Susskind's Challenge to the Hartle-Hawking No-Boundary Proposal and Possible Resolutions [PDF]

, 2006
Given the observed cosmic acceleration, Leonard Susskind has presented the following argument against the Hartle-Hawking no-boundary proposal for the quantum state of the universe: It should most likely lead to a nearly empty large de Sitter universe ...
Adams D, Aguirre A Gratton S Johnson M C, Alam U, Banks T, Boltzmann L, Bousso R, Bousso R, Bousso R, Bousso R Freivogel B, Carr B J, Ceresole A Dall’Agata G Giryavets A Kallosh R Linde A, Davies P C W, Deser S, Deutsch D, Don N Page, Dyson F, Dyson L, Easther R, Eddington A S, Firouzjahi H, Frievogel B, Frievogel B Sekino Y Susskind L Yeh C-P, Garriga J, Gell-Mann M, Gibbons G W Turok N, Goheer N, Halliwell J J, Halliwell J J, Hartle J B, Hawking S W, Hawking S W, Hawking S W, Hawking S W, Hawking S W, Hawking S W De Vega H J Sanchez N, Henneaux M, James W, Kallosh R, Kallosh R, Leslie J, Liddle A R, Linde A, Linde A, Linde A, Linde A, Linde A D, Linde A D, Linde A D, Linde A D, Linde A D, Linde A D, Linde A D, Lodge O, Ooguri H Vafa C, Page D N, Page D N, Page D N, Page D N, Page D N, Page D N, Page D N, Page D N, Page D N, Page D N, Page D N, Penrose R, Penrose R, Rees M J, Spergel D N, Starobinsky A A, Starobinsky A A, Susskind L, Susskind L, Susskind L, Tolman R C, Unruh W G Jheeta M, Vafa C, Vilenkin A, Vilenkin A, Vilenkin A, Vilenkin A, Vilenkin A, Vilenkin A, Vilenkin A, Vilenkin A, Vilenkin A, Vilenkin A Caldwell D O, Wang Y, Weinberg S, Weinberg S, Zel’dovich Ya B, Zel’dovich Ya B   +91 more
core   +4 more sources

The Maxwell–Chern–Simons gravity, and its cosmological implications

European Physical Journal C: Particles and Fields, 2017
We consider the cosmological implications of a gravitational theory containing two vector fields coupled via a generalized Chern–Simons term. One of the vector fields is the usual Maxwell field, while the other is a constrained vector field with constant
Zahra Haghani, Tiberiu Harko, Shahab Shahidi   +2 more
doaj   +1 more source

On quantum corrections to geodesics in de-Sitter spacetime

European Physical Journal C: Particles and Fields, 2021
We find a coordinate-independent wave-packet solution of the massive Klein–Gordon equation with the conformal coupling to gravity in the de-Sitter universe.
Viacheslav A. Emelyanov
doaj   +1 more source

Vanishing Cosmological Constant in Modified Gauss-Bonnet Gravity with Conformal Anomaly [PDF]

, 2006
We consider dark energy cosmology in a de Sitter universe filled with quantum conformal matter. Our model represents a Gauss-Bonnet model of gravity with contributions from quantum effects. To the General Relativity action an arbitrary function of the GB
Bergshoeff E. A., Brevik I., Calcagni G., Carter B. M. N., Cline J. M., Felder G. N., Garousi M. R., Guo Z. K., IVER BREVIK, JOHN QUIROGA, Kofman L., Nojiri S., Quiroga J., Quiroga J., Raeymaekers J., Sen A., Sen A., Sen A., Sen A.   +18 more
core   +3 more sources

Emergent dark matter in late time universe on holographic screen

Journal of High Energy Physics, 2018
We discuss a scenario that the dark matter in late time universe emerges as part of the holographic stress-energy tensor on the hypersurface in higher dimensional flat spacetime.
Rong-Gen Cai, Sichun Sun, Yun-Long Zhang
doaj   +1 more source

Islands in proliferating de Sitter spaces

Journal of High Energy Physics, 2023
We study two-dimensional de Sitter universe which evolves and proliferates according to the Ginsparg-Perry-Bousso-Hawking mechanism, using Jackiw-Teitelboim gravity coupled to conformal matter.
Jong-Hyun Baek, Kang-Sin Choi
doaj   +1 more source

Negative phase velocity of electromagnetic waves and the cosmological constant

, 2004
Examining the propagation of electromagnetic plane waves with the wavevector directed in opposition to the time-averaged Poynting vector in cosmological spacetime with piecewise uniform metric, we show that such negative-phase-velocity (NPV) propagation ...
Lakhtakia, Akhlesh, Mackay, Tom G., Setiawan, Sandi   +2 more
core   +3 more sources