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In a quest to explain the small value of the today's cosmological constant, following the approach introduced in [1], we show that the theoretical value of cosmological constant is consistent with its observational value. In more detail, we…

General Relativity and Quantum Cosmology · Physics 2015-10-08 T. Rostami , S. Jalalzadeh

A non-commutative multi-dimensional cosmological model is introduced and used to address the issues of compactification and stabilization of extra dimensions and the cosmological constant problem. We show that in such a scenario these…

High Energy Physics - Theory · Physics 2009-11-11 N. Khosravi , S. Jalalzadeh , H. R. Sepangi

The problem of the physical nature and the cosmological genesis of Lambda-term is discussed. This problem can't be solved in terms of the current quantum field theory which operates with Higgs and non-perturbative vacuum condensates and…

General Relativity and Quantum Cosmology · Physics 2007-05-23 V. Burdyuzha , O. Lalakulich , G. Vereshkov , Yu. Ponomarev

This essay elucidates recent achievements of the "nongravitating vacuum energy" (NGVE) theory" which has the feature that a shift of the Lagrangian density by a constant does not affect dynamics. In the first order formalism, a constraint…

General Relativity and Quantum Cosmology · Physics 2009-10-31 E. I. Guendelman , A. B. Kaganovich

We elaborate on the proposal of [Phys. Rev. Lett. 123 (2019) 13, 131302], about the possibility of hiding the cosmological constant in the complicated topology that one expects to exist at the Planck scale. We build a differential equation…

General Relativity and Quantum Cosmology · Physics 2020-11-25 Oliver F. Piattella

Well tempering is one of the few classical field theory methods for solving the original cosmological constant problem, dynamically canceling a large (possibly Planck scale) vacuum energy and leaving the matter component intact, while…

Cosmology and Nongalactic Astrophysics · Physics 2021-01-15 Stephen Appleby , Eric V. Linder

We propose several covariant models which may solve one of the problems in the cosmological constant. One of the model can be regarded as an extension of sequestering model. Other models could be regarded as extensions of the covariant…

High Energy Physics - Theory · Physics 2016-11-10 Shin'ichi Nojiri

The presence of a cosmological constant, Lambda, in an action with higher powers of the curvature can produce rapidly oscillating metrics. We develop a perturbative approach for generating periodic solutions to the non-linear field…

High Energy Physics - Theory · Physics 2009-11-07 Hael Collins , Bob Holdom

The value of the cosmological constant arising from a crystalline model for vacuum cosmic space with lattice parameter of the order of the neutron radius [1] has been calculated. The model allows to solve, in an easy way, the problem of the…

In this paper, we give a possible solution to the cosmological constant problem. It is shown hat the traditional approach, based on volume weighting of probabilities, leads to an incoherent onclusion: the probability that a randomly chosen…

General Relativity and Quantum Cosmology · Physics 2015-06-04 Artyom V. Astashenok , Antonino Del Popolo

We discuss the entropy and the size/homogeneity/horizon problems in power-law expanding universes with one scale initial conditions. We set the minimal scale $\Lambda = 10^{25}$ GeV at which a non-inflationary solution is possible and show…

High Energy Physics - Phenomenology · Physics 2009-01-07 Natalia Shuhmaher

We study cosmology of the Einstein-Yang-Mills theory in ten dimensions with a quartic term in the Yang-Mills field strength. We obtain analytically a class of cosmological solutions in which the extra dimensions are static and the scale…

High Energy Physics - Theory · Physics 2009-09-08 Hironobu Kihara , Muneto Nitta , Misao Sasaki , Chul-Moon Yoo , Ignacio Zaballa

The existence of a non-zero cosmological constant $\Lambda$ gives rise to controversial interpretations. Is $\Lambda$ a universal constant fixing the geometry of an empty universe, as fundamental as the Planck constant or the speed of light…

General Relativity and Quantum Cosmology · Physics 2012-09-25 Jean-Pierre Gazeau , Mario Novello

According to general relativity, the present analysis shows on geometrical grounds that the cosmological constant problem is an artifact due to the unfounded link of this fundamental constant to vacuum energy density of quantum…

General Relativity and Quantum Cosmology · Physics 2007-05-23 R. Triay

We use the quantum unimodular theory of gravity to relate the value of the cosmological constant, $\Lambda$, and the energy scale for the emergence of cosmological classicality. The fact that $\Lambda$ and unimodular time are complementary…

High Energy Physics - Theory · Physics 2023-01-04 Niayesh Afshordi , João Magueijo

The current observations seem to suggest that the universe has a positive cosmological constant of the order of $H_0^2$ while the most natural value for the cosmological constant will be $L_P^{-2}$ where $L_P = (G\hbar/c^3)^{1/2}$ is the…

General Relativity and Quantum Cosmology · Physics 2009-11-07 T. Padmanabhan

With the basic cosmological relations that agree with the recent observations, simple expressions are suggested concerning the value of cosmological constant($\Lambda$). A large contribution of quantum vacuum to the energy momentum tensor…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Ishwaree P. Neupane

We consider multidimensional gravitational models with a nonlinear scalar curvature term and form fields in the action functional. In our scenario it is assumed that the higher dimensional spacetime undergoes a spontaneous compactification…

High Energy Physics - Theory · Physics 2007-05-23 U. Guenther , P. Moniz , A. Zhuk

The idea that the cosmological term, Lambda, should be a time dependent quantity in cosmology is a most natural one. It is difficult to conceive an expanding universe with a strictly constant vacuum energy density, namely one that has…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-18 Joan Sola

We present a simple model where the effective cosmological constant appears from chameleon scalar fields. For a Kachru-Kallosh-Linde-Trivedi (KKLT)-inspired form of the potential and a particular chameleon coupling to the local density,…

High Energy Physics - Theory · Physics 2016-08-03 Horatiu Nastase , Amanda Weltman