Related papers: On Primordial Density Perturbation and Decaying Sp…
We show that the primordial density field imposes certain degree of coherence in the orientation of density perturbations. We quantify the scale of coherence and show that is significant on scales of at least $30-40h^{-1}$Mpc, being more…
We demonstrate that at long times the rate of passive scalar decay in a turbulent, or simply chaotic, flow is dominated by regions (in real space or in inverse space) where mixing is less efficient. We examine two situations. The first is…
We study the effect of varying sound speed on clustering dark energy in the Dirac-Born-Infeld (DBI) scenario. The DBI action is included in the class of $k$-essence models, and it has an important role in describing the effective degrees of…
Tunneling in the presence of an opaque barrier, part of which varies in time, is investigated numerically and analytically in one dimension. Clearly, due to the varying barrier a tunneling particle experiences spectral widening. However, in…
The sound velocity $v_s$ and dimensionless tidal deformability $\Lambda$ are analyzed using the pseudo-conformal model we developed before. In contrast to the conclusion obtained in the previous works in the literature, our model with the…
We show that dissipative effects during cosmological first order phase transitions lead to a frequency-dependent suppression for the usually dominant gravitational wave production from sound waves, through an analytical modelling of the…
The physical properties of our universe at energy scales above the expansion rate during inflation can affect predictions for the ratio between the amplitudes of the primordial scalar and tensor fluctuations. In particular, we study here…
If the large scale anomalies in the temperature power spectrum of the cosmic microwave background are of primordial origin, they may herald modifications to the slow roll inflationary paradigm on the largest scales. We study the possibility…
We present a gauge invariant formalism to study the evolution of curvature perturbations during decay of the inflaton or some other field that dominates the energy density. We specialize to the case where the total curvature perturbation…
The effects of phase space deformations in standard scalar field cosmology are studied. The deformation is introduced by modifying the symplectic structure of the minisuperspace variables to have a deformed Poisson algebra among the…
Disorder modifies the sound-wave excitation spectrum of Bose-Einstein condensates. We consider the classical hydrodynamic limit, where the disorder correlation length is much longer than the condensate healing length. By perturbation…
We show that an axionlike field coupled to a new confining gauge group can generate the primordial density perturbation in the post-inflation universe. The axion decay constant and strong coupling scale are uniquely determined by…
We consider primordial spectra with simple power behaviours and show that in the Navier-Stokes and magnetohydrodynamics equations without forcing, there exists systems in three dimensions with a subsequent inverse cascade, transferring…
Scalar field with generalized kinetic interactions metamorphoses depending on its field value, ranging from cosmological constant to stiff matter. We show that such a scalar field can give rise to temporal enhancement of the curvature…
The stability of particles in the cosmic soup is an important property that can affect the cosmic evolution. In this work, we update the constraints on the decaying cold dark matter scenario, when the decay products are effectively…
The evolution of scalar linear perturbations is studied in gauge-invariant approach for 2-component models with nonrelativistic matter and minimally coupled scalar fields, the potentials of which were constructed for either constant dark…
I discuss a mechanism that renders the spectral index of the primordial spectrum and the inflationary stage independent of each other. If a scalar field acquires an appropriate time-dependent mass, it is possible to generate an adiabatic,…
Within the framework of spatially covariant theories, we propose a general model for dark energy (DE) in which the cosmological background and perturbations are independently controlled by different sets of coefficients, and the equation of…
We study the intermittency and noise of dislocation systems undergoing shear deformation. Simulations of a simple two-dimensional discrete dislocation dynamics model indicate that the deformation rate exhibits a power spectrum scaling of…
We consider the consequences of a matter power spectrum which rises on small scales until eventually being cutoff by microphysical processes associated with the particle nature of dark matter. Evolving the perturbations of a weakly…