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After a short history of the $\Lambda$-term it is explained why the (effective) cosmological constant is expected to obtain contributions from short-distance physics, corresponding to an energy at least as large as the Fermi scale. The…

Astrophysics · Physics 2007-05-23 Norbert Straumann

Observations indicate that our universe is characterized by a late-time accelerating phase, possibly driven by a cosmological constant $\Lambda$, with the dimensionless parameter $\Lambda L_P^2 \simeq 10^{-122}$, where $L_P = (G \hbar…

General Relativity and Quantum Cosmology · Physics 2014-06-04 T. Padmanabhan , Hamsa Padmanabhan

We review arguments that the cosmological constant (c.c.) should not be thought of as a local contribution to the energy density, but rather as an infrared boundary condition specifying particular models of quantum gravity.

High Energy Physics - Theory · Physics 2018-11-13 Tom Banks , Willy Fischler

In this paper, time variable cosmological constant, dubbed {\it age cosmological constant}, is investigated motivated by the fact: any cosmological length scale and time scale can introduce a cosmological constant or vacuum energy density…

Cosmology and Nongalactic Astrophysics · Physics 2010-06-28 Lixin Xu , Jianbo Lu , Wenbo Li

A Universe with finite age also has a finite causal scale. Larger scales can not affect our local measurements or modeling, but far away locations could have different cosmological parameters. The size of our causal Universe depends on the…

General Physics · Physics 2020-04-17 Enrique Gaztanaga

The {\it{Cosmological Boundary Flux Parameter}} is a novel proposal that attempts to explain the origin of the cosmological parameter $\Lambda$ purely by geometric nature. Then we implement this new approach to a flat FLRW universe along…

General Relativity and Quantum Cosmology · Physics 2022-12-29 Rafael Hernández-Jiménez , Claudia Moreno , Mauricio Bellini , C. Ortiz

The main consequences of de Sitter Special Relativity to the Standard Cosmological Model of Physical Cosmology are examined. The cosmological constant Lambda appears, in this theory, as a manifestation of the proper conformal current, which…

General Relativity and Quantum Cosmology · Physics 2010-01-08 R. Aldrovandi , J. G. Pereira

We have investigated a cosmological model of a phantom energy with a variable cosmological constant ($\Lambda$) depending on the energy density ($\rho$) as $\Lambda\propto \rho^{-\alpha}$, $\alpha=\rm const.$ and a variable gravitational…

High Energy Physics - Theory · Physics 2008-12-25 Arbab I. Arbab

The cosmological constant $\Lambda$ is a measure of the energy density of the vacuum. Therefore properties of the energy of the system in the metastable vacuum state reflect properties of $\Lambda = \Lambda(t)$. We analyze properties of the…

General Relativity and Quantum Cosmology · Physics 2022-03-23 Krzysztof Urbanowski

With attempts to quench the cosmological constant $\Lambda$ having so far failed, we instead investigate what could be done if $\Lambda$ is not quenched and actually gets to be as big as elementary particle physics suggests. Since the…

Astrophysics · Physics 2007-05-23 Philip D. Mannheim

Combining general relativity and gravitational gauge theory, the cosmological constant is determined theoretically. The cosmological constant is related to the average vacuum energy of gravitational gauge field. Because the vacuum energy of…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Ning Wu , Germano Resconi , Zhan Xu , Zhi-Peng Zheng , Da-Hua Zhang , Tu-Nan Ruan

We study the role of the cosmological constant (CC) as a component of dark energy (DE). It is argued that the cosmological term is in general unavoidable and it should not be ignored even when dynamical DE sources are considered. From the…

High Energy Physics - Theory · Physics 2011-01-13 Florian Bauer

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

In this year, in which we celebrate 100 years of the cosmological term, $\Lambda$, in Einstein's gravitational field equations, we are still facing the crucial question whether $\Lambda$ is truly a fundamental constant or a mildly evolving…

Cosmology and Nongalactic Astrophysics · Physics 2017-09-27 Joan Sola , Adria Gomez-Valent , Javier de Cruz Perez

After a short history of the $\Lambda$-term it is explained why the (effective) cosmological constant is expected to obtain contributions from short-distance-physics, corresponding to an energy scale of at least 100 GeV. The actual tiny…

Astrophysics · Physics 2009-10-31 N. Straumann

Everpresent $\Lambda$ is a cosmological scenario in which the observed cosmological "constant" $\Lambda$ fluctuates between positive and negative values with a vanishing mean, and with a magnitude comparable to the critical density at any…

General Relativity and Quantum Cosmology · Physics 2018-10-17 Nosiphiwo Zwane , Niayesh Afshordi , Rafael D. Sorkin

We investigate the gravitational property of the quantum vacuum by treating its large energy density predicted by quantum field theory seriously and assuming that it does gravitate to obey the equivalence principle of general relativity. We…

General Relativity and Quantum Cosmology · Physics 2019-04-22 Qingdi Wang , Zhen Zhu , William G. Unruh

The energy density of the vacuum, Lambda, is at least 60 orders of magnitude smaller than several known contributions to it. Approaches to this problem are tightly constrained by data ranging from elementary observations to precision…

High Energy Physics - Theory · Physics 2008-11-26 Raphael Bousso

A mechanism for suppressing the cosmological constant is developed, based on an analogy with a superconducting phaseshift in which free fermions coupled perturbatively to a weak gravitational field are in an unstable false vacuum state. The…

High Energy Physics - Theory · Physics 2007-05-23 Stephon Alexander , Manasse Mbonye , John Moffat

We have shown that the phenomenological models with a cosmological constant of the type $\Lambda=\beta(\frac{\ddot R}{R})$ and $\Lambda=3\alpha H^2$, where $R$ is the scale factor of the universe and $H$ is the Hubble constant, are…

Astrophysics · Physics 2007-05-23 Arbab I. Arbab