相关论文: Cosmological perturbations from an inhomogeneous p…

In this brief note we present a set of equations describing the evolution of perturbed scalar fields in a cosmological spacetime with multiple scalar fields. We take into account of the simultaneously excited full metric perturbations in…

Cosmological phase transitions are thought to have taken place at the early Universe imprinting their properties on the observable Universe. There is strong evidence that, through the dynamics of a scalar field that lead a second order…

We argue that standard tools of holography can be used to describe fully non-perturbative microscopic models of cosmology in which a period of accelerated expansion may result from the positive potential energy of time-dependent scalar…

Models in which dark energy interacts with dark matter have been proposed in the literature to help explain why dark energy should only come to dominate in recent times. In this paper, we present a dynamical framework to calculate…

We discuss the effects of cosmic phase transition on the spectrum of primordial gravitational waves generated during inflation. The energy density of the scalar condensation responsible for the phase transition may become sizable at the…

If cosmological perturbations in our Hubble sized volume are nongaussian, then they will be coupled to any larger perturbation modes outside our Hubble volume. This has important consequences for modeling inflation: the scalar power…

The particle production process is reviewed, through which cosmic inflation can produce a scale invariant superhorizon spectrum of perturbations of suitable fields starting from their quantum fluctuations. Afterwards, in the context of the…

Cosmological models often contain scalar fields, which can acquire global nonzero expectation values that change with the comoving time. Among the possible consequences of these scalar-field backgrounds, an accelerated cosmological…

We compute the spectrum of cosmological perturbations in a scenario in which inflation is driven by radiation in a non-commutative space-time. In this scenario, the non-commutativity of space and time leads to a modified dispersion relation…

We show that the entropy of cosmological perturbations originating as quantum vacuum fluctuations in the very early universe, including the contribution of the leading nonlinear interactions, can be viewed as momentum space entanglement…

We discuss relationship between inflation and various models of production of density inhomogeneities due to strings, global monopoles, textures and other topological and non-topological defects. Neither of these models leads to a…

Several models of baryo(lepto)-genesis that give rise to large inhomogeneities in the composition of the universe are presented. In particular, a variation of primordial abundances of light elements by the factor 2-5 at large distances is…

We study the conditions under which thermal fluctuations generated in the contracting phase of a non-singular bouncing cosmology can lead to a scale-invariant spectrum of cosmological fluctuations at late times in the expanding phase. We…

We study the process whereby quantum cosmological perturbations become classical within inflationary cosmology. By setting up a master-equation formulation we show how quantum coherence for super-Hubble modes can be destroyed by their…

We consider scalar perturbations of energy-density for a class of cosmological models where an early phase of accelerated expansion evolves, without any fine-tuning for graceful exit, towards the standard Friedman eras of observed universe.…

Advantages of inhomogeneous cosmological models that are exact solutions of Einstein's equations over linearised perturbations of homogeneous models are presented. Examples of effects that can be described in the inhomogeneous ones are…

Cosmological phase transitions accompanied by some kind of symmetry breaking would cause the creation of topological defects and the resulting production of primordial magnetic field. Moreover, such a procedure inevitably affects the cosmic…

Particle phase transitions in the early universe including electroweak and grand unification ones are well-studied subjects. We point out that there are new possible particle phase transitions around inflation. Those new inflationary…

I show that cosmological perturbation spectra produced from quantum fluctuations in massless or self-interacting scalar fields during an inflationary era remain invariant under a two parameter family of transformations of the homogeneous…

Observations indicate that large-scale anomalies exist in the fluctuations of the cosmic microwave background. In these anomalies, the hemispherical power amplitude asymmetry has a correlation length comparable to that of the observable…