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We investigate the cosmological behavior in a universe governed by time asymmetric extensions of general relativity, which is a novel modified gravity based on the addition of new, time-asymmetric, terms on the Hamiltonian framework, in a…

General Relativity and Quantum Cosmology · Physics 2015-11-11 Genly Leon , Emmanuel N. Saridakis

The exact solutions for linear cosmological perturbations which have been obtained for collisionless relativistic matter within thermal field theory are extended to a self-interacting case. The two-loop contributions of scalar…

General Relativity and Quantum Cosmology · Physics 2009-12-30 H. Nachbagauer , A. K. Rebhan , D. J. Schwarz

Bermann [ Nuovo Cimento B (1983), 74, 182 ] presented a law of variation of Hubble parameter that yields constant deceleration parameter models of the Universe. In this paper, we study some cosmological models with negative constant…

General Relativity and Quantum Cosmology · Physics 2016-04-26 F. Rahaman , N. Begum , G. Bag , B. C. Bhui

It is observed that one of Einstein-Friedmann's equations has formally the aspect of a Sturm-Liouville problem, and that the cosmological constant, $\Lambda$, plays thereby the role of spectral parameter (what hints to its connection with…

Cosmology and Nongalactic Astrophysics · Physics 2012-12-19 Artyom V. Yurov , Artyom V. Astashenok , E. Elizalde

The $q$-theory approach to the cosmological constant problem is reconsidered. The new observation is that the effective classical $q$-theory gets modified due to the backreaction of quantum-mechanical particle production by spacetime…

High Energy Physics - Theory · Physics 2016-09-13 F. R. Klinkhamer , G. E. Volovik

A long-standing problem of theoretical physics is the exceptionally small value of the cosmological constant $\Lambda \sim 10^{-120}$ measured in natural Planckian units. Here we derive this tiny number from a toroidal string cosmology…

High Energy Physics - Theory · Physics 2011-07-19 Mar Bastero-Gil , Paul H. Frampton , Laura Mersini

We present a detailed investigation of the dynamical behavior of mimetic gravity with a general potential for the mimetic scalar field. Performing a phase-space and stability analysis, we show that the scenario at hand can successfully…

General Relativity and Quantum Cosmology · Physics 2018-12-13 Jibitesh Dutta , Wompherdeiki Khyllep , Emmanuel N. Saridakis , Nicola Tamanini , Sunny Vagnozzi

We derive new limits on the value of the cosmological constant, $\Lambda$, based on the Einstein bending of light by systems where the lens is a distant galaxy or a cluster of galaxies. We use an amended lens equation in which the…

Astrophysics · Physics 2009-11-13 Mustapha Ishak , Wolfgang Rindler , Jason Dossett , Jacob Moldenhauer , Chris Allison

E. Verlinde obtained a generalized formula for the entropy of a conformal field theory. For this we consider a (n+1) dimensional closed radiation dominated FLWR in the context of the holographic principle. In this work we construct a…

General Relativity and Quantum Cosmology · Physics 2010-11-25 Thiago G. Prado , Marcos C. Verges

We construct the cosmological model to explain the cosmological constant problem. We built the extension of the standard cosmological model $\Lambda$CDM by consideration of decaying vacuum energy represented by the running cosmological…

Cosmology and Nongalactic Astrophysics · Physics 2015-07-08 Marek Szydlowski

We discuss from the condensed-matter point of view the recent idea that the Poisson fluctuations of cosmological constant about zero could be a source of the observed dark energy. We argue that the thermodynamic fluctuations of Lambda are…

General Relativity and Quantum Cosmology · Physics 2009-11-10 G. E. Volovik

In this paper, we study the thermodynamical properties of the (2+1)dimensional black hole with a Coulomb-like electric field and the differential form of the first law of thermodynamics is derived considering a virtual displacement of its…

General Relativity and Quantum Cosmology · Physics 2012-11-07 Alexis Larranaga , Luz Angela Garcia

We argue that standard tools of holography can be used to describe fully non-perturbative microscopic models of cosmology in which a period of accelerated expansion may result from the positive potential energy of time-dependent scalar…

High Energy Physics - Theory · Physics 2022-03-23 Stefano Antonini , Petar Simidzija , Brian Swingle , Mark Van Raamsdonk

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

It is shown that the addition of a non-linear term to the Lagrangian of the electromagnetic field yields a fluid with an asymptotically super-negative equation of state, causing an accelerated expansion of the universe. Some general…

Astrophysics · Physics 2009-11-10 M. Novello , S. E. Perez Bergliaffa , J. Salim

In this Letter we consider three future singularities in different Friedmann-Lema\^{\i}tre-Robertson-Walker scenarios and show that the universe departs more and more from thermodynamic equilibrium as the corresponding singularity is…

General Relativity and Quantum Cosmology · Physics 2015-06-04 Diego Pavon , Winfried Zimdahl

In this paper we consider modification of general relativity extending $R - 2 \Lambda$ by nonlocal term of the form $\sqrt{R-2\Lambda}\, \mathcal{F}(\Box)\, \sqrt{R-2\Lambda} ,$ where $\mathcal{F}(\Box)$ is an analytic function of the…

General Relativity and Quantum Cosmology · Physics 2019-09-04 I. Dimitrijevic , B. Dragovich , A. S. Koshelev , Z. Rakic , J. Stankovic

In this work, which follows a series of studies on the higher-dimensional steady state universe idea and prepared for Professor Tekin Dereli's Festschrift, we show the influence of the dynamical internal (unobservable) space on the…

General Relativity and Quantum Cosmology · Physics 2022-02-23 Ozgur Akarsu , Tekin Dereli , Nihan Katirci

Some cosmological consequences of first order quantum corrections to Maxwell electrodynamics are investigated in the context of a spatially flat homogeneous and isotropic universe driven by a magnetic field plus a cosmological term…

Astrophysics · Physics 2007-05-23 M. R. de Garcia Maia , J. C. Carvalho , C. S. da Câmara Neto

General Relativity allows for a cosmological constant ($\Lambda$) which has inspired models of cosmic Inflation and Dark Energy. We show instead that $r_\Lambda = \sqrt{3/\Lambda}$ corresponds to an event horizon: a causal boundary term in…

Cosmology and Nongalactic Astrophysics · Physics 2022-02-02 Enrique Gaztanaga