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Gravitation and the standard model of particle physics are incorporated within a single conformal scalar-tensor theory, where the scalar field is complex. The Higgs field has a dynamical expectation value, as has the Planck mass, but the…

General Relativity and Quantum Cosmology · Physics 2017-03-24 Meir Shimon

We discuss the motivation for high accuracy relativistic gravitational experiments in the Solar System and complementary cosmological tests. We focus our attention on the issue of distinguishing a generic scalar-theory of gravity as the…

Astrophysics · Physics 2008-11-26 Orfeu Bertolami

A cosmic potential which can relax the vacuum energy is proposed in a framework of scalar-tensor gravity. In the phase of the gravity scalar field around the evolution with an approximate emergent conformal symmetry, we have obtained a set…

General Relativity and Quantum Cosmology · Physics 2013-08-30 Yongsung Yoon

We study a model of scalar field with a general non-minimal kinetic coupling to itself and to the curvature. The cosmological dynamics of this model and the issue of accelerated expansion is analyzed. Solutions giving rise to power law…

High Energy Physics - Theory · Physics 2011-01-17 L. N. Granda

The abundance of dark matter satellites and subhalos, the existence of density cusps at the centers of dark matter halos, and problems producing realistic disk galaxies in simulations are issues that have raised concerns about the viability…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 Joel R. Primack

In arXiv:1601.02203 and arXiv:1702.07063, we have proposed a topological model with a simple Lagrangian density and have tried to solve one of the cosmological constant problems. The Lagrangian density is the BRS exact and therefore the…

High Energy Physics - Theory · Physics 2018-02-14 Shin'ichi Nojiri

We analyse the role, on large cosmological scales and laboratory experiments, of the leading curvature squared contributions to the low energy effective action of gravity. We argue for a natural relationship $c_0\lambda^2\simeq 1$ at…

Cosmology and Nongalactic Astrophysics · Physics 2018-05-23 Philippe Brax , Patrick Valageas , Pierre Vanhove

We investigate the cosmological applications of new gravitational scalar-tensor theories, which are novel modifications of gravity possessing 2+2 propagating degrees of freedom, arising from a Lagrangian that includes the Ricci scalar and…

General Relativity and Quantum Cosmology · Physics 2016-06-22 Emmanuel N. Saridakis , Minas Tsoukalas

The cosmological history and evolution are examined for gravitational models with interaction in the dark sector of the universe. In particular, we consider the dark energy to be described by a phantom scalar field and the dark matter $\rho…

General Relativity and Quantum Cosmology · Physics 2024-12-11 Andronikos Paliathanasis , Amlan Halder , Genly Leon

This paper treats nonrelativistic matter and a scalar field $\phi$ with a monotonically decreasing potential minimally coupled to gravity in flat Friedmann-Lema\^{i}tre-Robertson-Walker cosmology. The field equations are reformulated as a…

General Relativity and Quantum Cosmology · Physics 2015-11-11 Artur Alho , Claes Uggla

Although the standard cosmological model, the so-called $\Lambda$ Cold Dark Matter ("$\Lambda$CDM"), appears to fit well observations at the cosmological level, it is well known that it possesses several inconsistencies at the galactic…

Astrophysics of Galaxies · Physics 2021-03-24 Luis E. Padilla , Jordi Solís-López , Tonatiuh Matos , Ana Ávilez-López

We study the formation of structure in the Universe assuming that dark matter can be described by a scalar field $\tilde{\Phi}$ with a potential $V(\Phi)=-\mathfrak{m}^{2}\tilde{\Phi}^{2}/2+\lambda\tilde{\Phi}^4/4$. We derive the evolution…

Cosmology and Nongalactic Astrophysics · Physics 2021-02-09 Juan Magaña , Tonatiuh Matos , Abril Suárez , F. J. Sánchez-Salcedo

We propose a relativistic model of dark matter reproducing at once the concordance cosmological model $\Lambda$-Cold-Dark-Matter ($\Lambda$-CDM) at cosmological scales, and the phenomenology of the modified Newtonian dynamics (MOND) at…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-17 Laura Bernard , Luc Blanchet

The cold dark matter (DM) paradigm describes the large-scale structure of the universe remarkably well. However, there exists some tension with the observed abundances and internal density structures of both field dwarf galaxies and…

Cosmology and Nongalactic Astrophysics · Physics 2012-12-07 Laura G. van den Aarssen , Torsten Bringmann , Christoph Pfrommer

We propose that dark energy in the form of a scalar field could effectively couple to dark matter inhomogeneities. Through this coupling energy could be transferred to/from the scalar field, which could possibly enter an accelerated regime.…

Cosmology and Nongalactic Astrophysics · Physics 2016-04-25 Valerio Marra

Structure formation at small cosmological scales provides an important frontier for dark matter (DM) research. Scenarios with small DM particle masses, large momenta or hidden interactions tend to suppress the gravitational clustering at…

Cosmology and Nongalactic Astrophysics · Physics 2017-11-27 Riccardo Murgia , Alexander Merle , Matteo Viel , Maximilian Totzauer , Aurel Schneider

Recent cosmological observations and compatible theory offer an understanding of long-mysterious dark matter and dark energy. The postulate of universal conformal local Weyl scaling symmetry, without dark matter, modifies action integrals…

General Physics · Physics 2021-09-22 R. K. Nesbet

In this work, we apply the formalism of dynamical systems to analyze the viability of the $\Lambda$CDM model in a generalized form of the hybrid metric-Palatini gravity theory written in terms of its dynamically equivalent scalar-tensor…

General Relativity and Quantum Cosmology · Physics 2024-09-06 João Luís Rosa

The Reduced Relativistic Gas (RRG) model was introduced by A. Sakharov in 1965 for deriving the cosmic microwave background (CMB) spectrum. It was recently reinvented by some of us to achieve an interpolation between the radiation and dust…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-18 Julio. C. Fabris , Alan M. Velasquez-Toribio , Winfried Zimdahl , Ilya L. Shapiro

In previous work [L. Blanchet and A. Le Tiec, Phys. Rev. D 78, 024031 (2008)], a model of dark matter and dark energy based on the concept of gravitational polarization was investigated. This model was shown to recover the concordance…

Cosmology and Nongalactic Astrophysics · Physics 2010-04-15 Luc Blanchet , Alexandre Le Tiec