Related papers: Astrophysical constraints on unparticle-inspired m…
Within the thermodynamic model of gravity the dark energy is identified with the energy of collective gravitational interactions of all particles in the universe, which is missing in the standard treatments. For the model-universe we…
The energy density of a scalar field $\phi$ with potential $V(\phi) \propto \phi^{-\alpha}$, $\alpha > 0$, behaves like a time-variable cosmological constant that could contribute significantly to the present energy density. Predictions of…
We discuss the stability of atoms and nucleons in the presence of multidimensional gravity characterized by the unified energy scale 1TeV. We point out that the multidimensional gravitational attraction can create additional bound states…
We demonstrate the viability of electroweak baryogenesis scenarios in which the necessary departure from equilibrium is realized by the evolution of a network of topological defects. We consider several effective models of TeV physics, each…
A range of experimental results point to the existence of a massive neutrino. The recent high precision measurements of the cosmic microwave background and the large scale surveys of galaxies can be used to place an upper bound on this…
The paper considers a set of equations describing the static isotropic gravity field of a macroscopic body within the framework of the theory of gravity with a constraint. A general approximate solution of these equations is obtained. The…
In general relativity, the energy conditions are invoked to restrict general energy-momentum tensors on physical grounds. We show that in the standard Friedmann-Lemaitre-Robertson-Walker approach to cosmological modelling where the equation…
A nontrivial topology of the spatial section of the universe is an observable, which can be probed for all locally homogeneous and isotropic universes, without any assumption on the cosmological density parameters. We discuss how one can…
We search for viable f(R) theories of gravity, making use of the equivalence between such theories and scalar-tensor gravity. We find that models can be made consistent with solar system constraints either by giving the scalar a high mass…
We study the screening mechanism in the most general scalar-tensor theories that leave gravitational waves unaffected and are thus compatible with recent LIGO/Virgo observations. Using the effective field theory of dark energy approach, we…
Recent advances in understanding the propagation of perturbations through the transition from big crunch to big bang (esp. Tolley et al. hep-th/0306109) make it possible for the first time to consider the full set of phenomenological…
We investigate the metric perturbations of the restricted f(R) theory of gravity in the cosmological context and explore the phenomenological implications of this model. We show that it is possible to construct a restricted model of…
$f(P)$ gravity is a novel extension of ECG in which the Ricci scalar in the action is replaced by a function of the curvature invariant $P$ which represents the contractions of the Riemann tensor at the cubic order \cite{p}. The present…
We calculate cosmological and astrophysical bounds on the couplings between standard model fields and tensor unparticles. The present day density of tensor unparticles from neutrino-neutrino and photon-photon annihilation is calculated.…
In this paper, we carry out a study of viable cosmological models in $f(R)$-gravity at the background level. We use observable parameters like $\Omega$ and $\gamma$ to form autonomous system of equations and show that the models under…
We evaluate regions of parameter space in the minimal supergravity model where ``unbounded from below'' (UFB) or charge or color breaking minima (CCB) occur. Our analysis includes the most important terms from the 1-loop effective…
We show that the recently proposed weak gravity conjecture\cite{AMNV0601} can be extended to a class of scalar field theories. Taking gravity into account, we find an upper bound on the gravity interaction strength, expressed in terms of…
Recently, gravitational microlensing has been investigated in the framework of the weak field limit of fourth order gravity theory. However, solar system data (i.e. planetary periods and light bending) can be used to put strong constraints…
We study observational constraints on the modified symmetric teleparallel gravity, the non-metricity $f(Q)$ gravity, which reproduces background expansion of the universe. For this purpose, we use Hubble measurements, Baryonic Acoustic…
Conventional particle theories such as the Standard Model have a number of freely adjustable coupling constants and mass parameters, depending on the symmetry algebra of the local gauge group and the representations chosen for the spinor…