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The observed value of the cosmological constant poses large theoretical problems. We find that topology of the Universe provides a natural source for it. Restricting dynamically an Einstein-Cartan gravity to General Relativity in our…

General Relativity and Quantum Cosmology · Physics 2020-06-16 M. Le Delliou , J. Lorca Espiro

The concept of exotic charged dust is introduced here to represent dark matter. The term "exotic" means that the dust is not composed of normal matter, and the charge--for lack of a better term--is not an electric charge. It is also shown…

General Physics · Physics 2025-04-23 Gerald E. Marsh

Under the assumption that General Relativity (GR) correctly describes the phenomenology of our Universe, astronomical observations provide compelling evidence that (1) the dynamics of cosmic structure is dominated by dark matter (DM), an…

Astrophysics · Physics 2008-02-19 A. Diaferio

We propose that the solution to the cosmological vacuum energy puzzle may come from the infrared sector of the effective theory of gravity, where the impact of the trace anomaly is of upmost relevance. We proceed by introducing two…

General Relativity and Quantum Cosmology · Physics 2009-08-12 Evan C. Thomas , Federico R. Urban , Ariel R. Zhitnitsky

It will be argued here that the cosmological constant problem exists because of the way the vacuum is defined in quantum field theory. It has been known for some time that for QFT to be gauge invariant certain terms--such as part of the…

General Relativity and Quantum Cosmology · Physics 2008-06-20 Gerald E. Marsh

Observational evidence indicating that the expansion of the universe is accelerating has surprised cosmologists in recent years. Cosmological models have sought to explain this acceleration by incorporating `dark energy', of which the…

Astrophysics · Physics 2010-03-26 Luke Barnes , Matthew J. Francis , Geraint F. Lewis , Eric V. Linder

Quantum theory, general relativity, the standard model of particle physics, and the $\Lambda$CDM model of cosmology have all been spectacularly successful within their respective regimes of applicability, but many central problems remain…

General Physics · Physics 2026-05-26 Roland E. Allen

Vacuum energy changes during cosmological phase transitions and becomes relatively important at epochs just before phase transitions. For a viable cosmology the vacuum energy just after a phase transition must be set by the critical…

Cosmology and Nongalactic Astrophysics · Physics 2016-07-20 Brando Bellazzini , Csaba Csaki , Jay Hubisz , Javi Serra , John Terning

It has been suggested that the Dark Energy Coincidence Problem could be interpreted as a possible link between the cosmological constant and a massive graviton. We show that by using that link and models for the graviton mass a dark energy…

General Relativity and Quantum Cosmology · Physics 2009-11-11 M. Tajmar

The cosmological constant (CC) problem is the biggest enigma of theoretical physics ever. In recent times, it has been rephrased as the dark energy problem in order to encompass a wider spectrum of possibilities. It is, in any case, a…

High Energy Physics - Theory · Physics 2009-07-23 Florian Bauer , Joan Sola , Hrvoje Stefancic

We reexamine the surface composition of strange stars. Strange quark stars are hypothetical compact stars which could exist if strange quark matter was absolutely stable. It is widely accepted that they are characterized by an enormous…

Nuclear Theory · Physics 2007-05-23 Prashanth Jaikumar , Sanjay Reddy , Andrew W. Steiner

The Cosmological Constant Problem is re-examined from an effective field theory perspective. While the connection between gravity and particle physics has not been experimentally probed in the quantum regime, it is severely constrained by…

High Energy Physics - Phenomenology · Physics 2009-10-30 Raman Sundrum

Some form of missing energy may account for the difference between the observed cosmic matter density and the critical density. Two leading candidates are a cosmological constant and quintessence (a time-varying, inhomogenous component with…

Astrophysics · Physics 2009-09-15 Greg Huey , Limin Wang , R. Dave , R. R. Caldwell , Paul J. Steinhardt

The cosmological constant problem is reviewed and a possible quantum gravity resolution is proposed. A space satellite E\"otv\"os experiment for zero-point vacuum energy is proposed to see whether Casimir vacuum energy falls in a…

General Relativity and Quantum Cosmology · Physics 2007-05-23 J. W. Moffat

Observations provide increasingly strong evidence that the universe is accelerating. This revolutionary advance in cosmological observations confronts theoretical cosmology with a tremendous challenge, which it has so far failed to meet.…

Astrophysics · Physics 2008-11-26 Ruth Durrer , Roy Maartens

Because of the mass density-dependence, an extra term should be added to the expression of pressure. However, it should not appear in that of energy according to both the general ensemble theory and basic thermodynamic principle. We give a…

High Energy Physics - Phenomenology · Physics 2009-10-31 G. X. Peng , H. C. Chiang , P. Z. Ning

A variety of observations indicate that the universe is dominated by dark energy with negative pressure, one possibility for which is a cosmological constant. If the dark energy is a cosmological constant, a fundamental question is: Why has…

Astrophysics · Physics 2008-11-26 Maqbool Ahmed , Scott Dodelson , Patrick B. Greene , Rafael Sorkin

The discovery of accelerated cosmic expansion implies that, in addition to the attractive gravity of matter, there exists in our universe some other form of energy (dark energy or cosmological constant) producing a repulsive force. The…

General Physics · Physics 2013-03-26 Ti-Pei Li

The cosmological constant problem is studied in a two component cosmological model. The universe contains a cosmological constant of an arbitrary size and sign and an additional component with an inhomogeneous equation of state. It is shown…

General Relativity and Quantum Cosmology · Physics 2009-01-16 Hrvoje Stefancic

We determine the Galactic production rate of strangelets as a canonical input to calculations of the measurable cosmic ray flux of strangelets by performing simulations of strange star mergers and combining the results with recent estimates…