Related papers: Scalar Non-Luminous Matter in Galaxies
In this work we investigate the possibility that a simple extension of the Standard Model (SM) can be the dark matter of the universe. We postulate the existence of a scalar field singlet like the Higgs as an extra term in the SM…
The recent observations of neutron star mergers have changed our perspective on scalar- tensor theories of gravity, favouring models where gravitational waves travel at the speed of light. In this work we consider a scalar-tensor set-up…
The Machian cosmological solution satisfying $\phi =O(\rho /\omega)$ in the generalized scalar-tensor theory of gravitation with the varying cosmological constant is summarized. The scalar field $\phi $ with the exponential potential is…
The problem of galactic formation and evolution should be solved on the basis of the Standard Model of particle physics. We believe that we live in the quantum 4-dimensional Minkowski space-time with the force-fields gauge-group structure…
We study a three-component universe filled with dust-like matter in the form of discrete inhomogeneities (e.g., galaxies) and perfect fluids characterized by linear and nonlinear equations of state. Within the cosmic screening approach, we…
Scalar-tensor gravitational theories are important extensions of standard general relativity, which can explain both the initial inflationary evolution, as well as the late accelerating expansion of the Universe. In the present paper we…
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…
Scalar fields appear in many cosmological models, in particular in order to provide explanations for dark energy and inflation, but also to emulate dark matter. In this paper, we show that it is possible for a scalar field to replace…
We examine the phenomenology of a low-energy extension of the Standard Model, based on the gauge group SU(3) x SU(2) x U(1) x SO(3), with SO(3) operating in the shadow sector. This model offers $\nu_{e} \to \nu_{s}$ and $\nu_{\mu} \to…
The kinematics of the outer parts of three intermediate-luminosity elliptical galaxies have been studied using the Planetary Nebula Spectrograph. The galaxies' velocity dispersion profiles are found to decline with radius; dynamical…
Deformations of the canonical spectral triples over the n-dimensional torus are considered. These deformations have a discrete dimension spectrum consisting of non-integer values less than n. The differential algebra corresponding to these…
We study a model of scalar field with kinetic terms non-minimally coupled to to the curvature, and the scalar field coupled to the Gauss Bonnet 4-dimensional invariant. A variety of solutions are found, giving rise to different cosmological…
We consider a model for cold dark matter, which combines a real scalar singlet and a real scalar $SU(2)_L$ triplet field, both of which are residing in the odd representation of a global $Z_2$ symmetry. The parameter space of the model is…
In this paper we investigate the problem of spontaneous supersymmetry breaking without a cosmological term in $N=3$ supergravity with matter vector multiplets, scalar fields geometry being $SU(3,m)/SU(3)\otimes SU(m)\otimes U(1)$. At first,…
In a previous work (Mbelek 2001), we modelled the rotation curves (RC) of spiral galaxies by including in the equation of motion of the stars the dynamical terms from an external real self-interacting scalar field, $\psi$, minimally coupled…
We examine the possibility that dark matter (DM) may be an ultralight scalar that was misaligned via non-minimal coupling to gravity, in the early Universe. For a certain regime of scalar masses, gravitational effects in neutron stars could…
A mysterious dark matter is supposed to exist in the galactic halos. In this contrast, we discuss the possibility of explaining the flat rotational velocity curves in f(R) gravity by solving field equations numerically in vacuum and for…
We show that in the framework of R^{2} gravity and in the linearized approach it is possible to obtain spherically symmetric stationary states that can be used as a model for galaxies. The model can also help to have a better understanding…
Ultra-light scalar fields may explain the nature of the dark matter in our universe. If such scalars couple quadratically to particles of the Standard Model the scalar acquires an effective mass which depends on the local matter energy…
We continue the study of the tensor-four-scalars theory which is a modification of general relativity. We include normal matter by applying the displace, cut, and reflect method to our previous vacuum solutions with dark halo. The resulting…