相关论文: Galactic periodicity and the oscillating G model
We consider the presence and evolution of primordial density perturbations in a cosmological model based on a simple ansatz which captures -- by providing a set of effective gravitational field equations -- the strength of the enhanced…
Quadratic curvature Gauss-Bonnet gravity may be the solution to the dark energy problem, but a large coupling strength is required. This can lead to conflict with laboratory and planetary tests of Newton's law, as well as light bending. The…
The subject of this paper is to investigate the weak regime covariant scalar-tensor-vector gravity (STVG) theory, known as the MOdified gravity (MOG) theory of gravity. First, we show that the MOG in the absence of scalar fields is…
Constraints on an exact quintessence scalar-field model with an exponential potential are derived from gravitational lens statistics. An exponential potential can account for data from both optical quasar surveys and radio selected sources.…
A huge value of cosmological constant characteristic for the particle physics and the inflation of early Universe are inherently related to each other: one can construct a fine-tuned superpotential, which produces a flat potential of…
Recent analyses that combine the latest data from the Atacama Cosmology Telescope (ACT) with cosmic microwave background observations by BICEP/Keck and Planck, together with the DESI baryon acoustic-baryonic-oscillation (BAO) measurements,…
We investigate the possibility of accounting for the currently inferred primordial abundances of D, 3He, 4He, and 7Li by big bang nucleosynthesis in the presence of baryon density inhomogeneities plus the effects of late-decaying massive…
The dynamic evolution of galactic bars in standard $\Lambda$CDM models is dominated by angular momentum loss to the dark matter haloes via dynamical friction. Traditional approximations to dynamical friction are formulated using the…
We argue that the SM in the Higgs phase does not suffer form a "hierarchy problem" and that similarly the "cosmological constant problem" resolves itself if we understand the SM as a low energy effective theory emerging from a cut-off…
Recent cosmological observations have provided numerous new observations with increasing precision that have led to the era of precision cosmology. The exquisite quality of these observations opens new possibilities towards measuring…
We propose a novel parameterization of the dark energy density. It is particularly well suited to describe a non-negligible contribution of dark energy at early times and contains only three parameters, which are all physically meaningful:…
We present a holographic dark-energy model in which the Newton constant $G_{N}$ scales in such a way as to render the vacuum energy density a true constant. Nevertheless, the model acts as a dynamical dark-energy model since the scaling of…
We use all available baryon acoustic oscillation distance measurements and Hubble parameter data to constrain the cosmological constant $\Lambda$, dynamical dark energy, and spatial curvature in simple cosmological models. We find that the…
A model is suggested to unify the Einstein GR and Dirac Cosmology. There is one adjusted parameter $b_2$ in our model. After adjusting the parameter $b_2$ in the model by using the supernova data, we have calculated the gravitational…
Cosmology is nowadays going through a true revolution in the quantity and quality of observations that are capable of providing crucial information about the origin and evolution of the universe. In the first years of the next millenium we…
In this work, we derive upper limits on the physical energy-density fraction today of cosmological gravitational waves, denoted by $\Omega_{\rm{gw}}h^{2}$, via analyzing \emph{Planck} \& ACT \& SPT CMB and DESI BAO data combination. In the…
A generic feature of viable $F(R)$ gravity is investigated: It is demonstrated that during the matter dominated era the large frequency oscillations of the effective dark energy may influence the behavior of higher derivatives of the Hubble…
The current expansion of the Universe has been observed to be accelerating, and the widely accepted spatially-flat concordance model of general relativistic cosmology attributes this phenomenon to a constant dark energy, a cosmological…
Big-bang nucleosynthesis is one of the cornerstones of the standard cosmology. For almost thirty years its predictions have been used to test the big-bang model to within a fraction of a second of the bang. The concordance that exists…
We quantify the accuracy with which the cosmological parameters characterizing the energy density of matter (\Omega_m), the amplitude of the power spectrum of matter fluctuations (\sigma_8), the energy density of neutrinos (\Omega_{\nu})…