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Related papers: Simple numerical implementation of general dark en…

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By using the effective field theory approach, we investigate the role of initial condition for the dark energy or modified gravity models. In details, we consider the constant and linear parametrization of the effective Newton constant…

Cosmology and Nongalactic Astrophysics · Physics 2018-01-10 Xue-Wen Liu , Bin Hu , Yi Zhang

We show that the dark energy effects can be modeled by using an \emph{Ising perfect fluid} with network interactions, whose low redshift equation of state, i.e. $\omega_0$, becomes $\omega_0=-1$ as in the $\Lambda$CDM model. In our picture,…

High Energy Physics - Theory · Physics 2015-06-15 Orlando Luongo , Damiano Tommasini

We develop an approach to compute observables beyond the linear regime of dark matter perturbations for general dark energy and modified gravity models. We do so by combining the Effective Field Theory of Dark Energy and Effective Field…

Cosmology and Nongalactic Astrophysics · Physics 2020-01-07 Giulia Cusin , Matthew Lewandowski , Filippo Vernizzi

We discuss the limitations to the use of the effective field theory approach to study dark matter at the LHC. We introduce and study a few quantities, some of them independent of the ultraviolet completion of the dark matter theory, which…

High Energy Physics - Phenomenology · Physics 2013-12-20 Giorgio Busoni , Andrea De Simone , Enrico Morgante , Antonio Riotto

The universe content is considered as a non-perfect fluid with bulk viscosity and can be described by a general equation of state (endowed some deviation from the conventionally assumed cosmic perfect fluid model). An explicitly bulk…

Astrophysics · Physics 2009-10-16 X H Meng , X Dou

Cosmological observations are normally fit under the assumption that the dark sector can be decomposed into dark matter and dark energy components. However, as long as the probes remain purely gravitational, there is no unique decomposition…

Cosmology and Nongalactic Astrophysics · Physics 2009-11-05 Martin Kunz , Andrew R Liddle , David Parkinson , Changjun Gao

We investigate the possibility of using cosmological observations to probe and constrain an imperfect dark energy fluid. We consider a general parameterization of the dark energy component accounting for an equation of state, speed of sound…

Astrophysics · Physics 2008-12-18 D. F. Mota , J. R. Kristiansen , T. Koivisto , N. E. Groeneboom

The coupling between the dark components provides a new approach to mitigate the coincidence problem of cosmological standard model. In this paper, dark energy is treated as a fluid with a constant equation of state, whose coupling with…

Cosmology and Nongalactic Astrophysics · Physics 2014-08-18 Weiqiang Yang , Lixin Xu

An effective formalism for quantum constrained systems is presented which allows manageable derivations of solutions and observables, including a treatment of physical reality conditions without requiring full knowledge of the physical…

Mathematical Physics · Physics 2009-03-12 Martin Bojowald , Barbara Sandhoefer , Aureliano Skirzewski , Artur Tsobanjan

Some dark energy cosmological models are constructed in the framework of a generalised Brans-Dicke theory which contains a self interacting potential and a dynamical coupling parameter. The dark sector of the universe is considered through…

General Relativity and Quantum Cosmology · Physics 2022-07-19 S. K. Tripathy , Sasmita K Pradhan , Z. Naik , D. Behera , B. Mishra

We explore an autonomous system analysis of dark energy models with interactions between dark energy and cold dark matter in a general systematic approach to cosmological fluids. We investigate two types of models such as local and…

General Relativity and Quantum Cosmology · Physics 2024-03-14 Parth Shah , Gauranga C. Samanta , Kazuharu Bamba , R. Myrzakulov

We present a methodology for computing model independent perturbations in dark energy and modified gravity. This is done from the Lagrangian for perturbations, by showing how field content, symmetries, and physical principles are often…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-18 Richard A. Battye , Jonathan A. Pearson

A model of unification of dark matter and dark energy based on the modeling of the speed of sound as a function of the parameter of the equation of state is introduced. It is found that the model in which the speed of sound depends on the…

Cosmology and Nongalactic Astrophysics · Physics 2013-04-04 Neven Caplar , Hrvoje Stefancic

Theoretical results on a conventional approach to the dark energy (DE) concept are reviewed and discussed. According to them, there is absolutely no need for a novel DE component in the Universe, provided that the associated matter-energy…

General Relativity and Quantum Cosmology · Physics 2023-06-19 Kostas Kleidis , Nikolaos K. Spyrou

All observational evidence for dark matter and dark energy is so far exclusively gravitational. Hence, the dark sector may be equivalently described by a theory of the spacetime metric whose dynamics is affected by interactions with an…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-10 Santiago Agüí Salcedo , Thomas Colas , Lennard Dufner , Enrico Pajer

In light of upcoming observations modelling perturbations in dark energy and modified gravity models has become an important topic of research. We develop an effective action to construct the components of the perturbed dark energy momentum…

High Energy Physics - Theory · Physics 2015-06-04 Richard A. Battye , Jonathan A. Pearson

We discuss a model of non perturbative decay of dark energy into hot and cold dark matter. This model provides a mechanism from the field theory to realize the energy transfer from dark energy into dark matter, which is the requirement to…

General Relativity and Quantum Cosmology · Physics 2015-06-04 Elcio Abdalla , Leila Graef , Bin Wang

This paper presents a generalized energy-based modeling framework extending recent formulations tailored for differential-algebraic equations. The proposed structure, inspired by the port-Hamiltonian formalism, ensures passivity, preserves…

Numerical Analysis · Mathematics 2026-01-06 Robert Altmann , Idoia Cortes Garcia , Elias Paakkunainen , Philipp Schulze , Sebastian Schöps

Combustion stabilization and enhancement of the flammability limits are mandatory objectives to improve nowadays combustion chambers. At this purpose, the use of an electric field in the flame region provides a solution which is, at the…

Fluid Dynamics · Physics 2017-12-13 M. Di Renzo , P. De Palma , M. D. de Tullio , G. Pascazio

We generalize to non-flat geometries the formalism of Simon et al. (2005) to reconstruct the dark energy potential. This formalism makes use of quantities similar to the Horizon-flow parameters in inflation, can, in principle, be made…

Astrophysics · Physics 2009-11-13 Enrique Fernandez-Martinez , Licia Verde