Related papers: Big Bounce Genesis
As one of the fundamental unknowns of our Universe, the mass of dark matter remains to be a topic of great interest. We consider the possibility of a time-variation of the dark matter mass. We study the cosmological constraints on a model…
We describe a new mechanism of dark matter production in the early Universe, based on the dynamics of a first order phase transition. We assume that dark matter particles acquire mass during the phase transition, making it energetically…
If the preon structure of quarks, leptons and gauge bosons will be proved then in the Universe during relativistic phase transition the production of nonperturbative preon condensates has been occured collective excitations of which are…
Once dark matter has been discovered and its particle physics properties have been determined, a crucial question rises concerning how it was produced in the early Universe. If its thermally averaged annihilation cross section is in the…
Holographic considerations are used in the scrutiny of a special class of brane-world cosmologies. Inherently to this class, the brane typically bounces, at a finite size, as a consequence of a charged black hole in the bulk. Whereas a…
We study the effects of modifying the expansions history of the Universe on Dark Matter freezeout. We derived a modified Boltzmann equation for freeze-out for an arbitrary energy density in the early Universe and provide an analytic…
We wonder if a cyclic universe may be dominated alternatively by matter and antimatter. Such a scenario demands a mechanism for transformation of matter to antimatter (or antimatter to matter) during the final stage of a big crunch. By…
General relativity predicts a singularity in the beginning of the universe being called big bang. Recent developments in loop quantum cosmology avoid the singularity and the big bang is replaced by a big bounce. A classical theory of…
Theoretically, the running of the cosmological constant in the IR region is not ruled out. On the other hand, from the QFT viewpoint, the energy released due to the variation of the cosmological constant in the late universe cannot go to…
The cosmic expansion history proceeds in broad terms from a radiation dominated epoch to matter domination to an accelerated, dark energy dominated epoch. We investigate whether intermittent periods of acceleration are possible in the early…
In the present universe visible and dark matter contribute comparable energy density although they have different properties. This coincidence can be elegantly explained if the dark matter relic density, originating from a dark matter…
Big bang nucleosynthesis (BBN), an epoch of primordial nuclear transformations in the expanding Universe, has left an observable imprint in the abundances of light elements. Precision observations of such abundances, combined with…
Preheating describes the stage of rapidly depositing the energy of cosmological scalar field into excitations of other light fields. This stage is characterized by exponential particle production due to the parametric resonance. We study…
We suggest an alternative framework for interpreting the current state of the visible universe. Our approach is based on a dynamical ``Cosmological Constant'' and the starting point is that a decaying vacuum produces matter. As we point…
We propose a mechanism to have a smooth transition from a pre-Big Bang phase to a standard cosmological phase. Such transition is driven by gravitational production of heavy massive string states that backreact on the geometry to stop the…
The discovery of universe's late-time acceleration and dark energy has overseen a great deal of research into cosmological singularities and particularly future singularities. Perhaps the most extreme of such singlarities is the big rip,…
The dark sector of the Universe is beginning to be clarified step by step. If the dark energy is vacuum energy, then 123 orders are exactly reduced by ordinary physical processes. For many years these unexplained orders were called a crisis…
The cosmological abundance of nucleons determined from considerations of Big Bang nucleosynthesis allegedly provides compelling evidence for non-nucleonic dark matter. Recent developments in measurements of primordial light element…
In the first section, I will try to convey a sense of the variety of observational inputs that tell us about the existence and the spatial distribution of dark matter in the universe. In the second section, I will briefly review the four…
The discovery that we live in an accelerating universe changed drastically the paradigm of physics and introduced the concept of \textit{dark energy}. In this work, we present a brief historical description of the main events related to the…