Related papers: Superheavy Particles in Friedmann Cosmology and th…
A highly excited Friedmann universe filled with a scalar field and radiation has been considered. On the basis of a direct solution to the quantum-mechanical problem with a well-defined time variable, it has been shown that such a universe…
More than sixty years ago Zwicky made the case that the great clusters of galaxies are held together by the gravitational force of unseen (dark) matter. Today, the case is stronger and more precise: Dark, nonbaryonic matter accounts for 30%…
Several lines of evidence suggest that some of the dark matter may be non-baryonic: the non-detection of various plausible baryonic candidates for dark matter inferred, e.g., from galaxy rotation curves and from cluster of galaxy velocity…
Recent spacecraft observations exploring solar system properties impact standard paradigms of the formation of stars, planets and comets. We stress the unexpected cloud of microscopic dust resulting from the DEEP IMPACT mission, and the…
In supergravity models, the evaporation of light Primordial Black Holes (PBHs) should be a source of gravitinos. By considering this process, new stringent limits are derived on the abundance of small black holes with initial masses less…
The recently observed Deuterium abundance in a low- metallicity high-redshift hydrogen cloud, which is about ten times larger than that observed in the near interstellar medium, is that expected from the Standard Big Bang Nucleosynthesis…
The distribution of the non-luminous matter in galaxies of different luminosity and Hubble type is much more than a proof of the existence of dark particles governing the structures of the Universe. Here, we will review the complex but…
After a brief introduction to standard cosmology and the dark matter problem in the the Universe, we consider a self-gravitating noninteracting fermion gas at nonzero temperature as a model for the dark matter halo of the Galaxy. This…
Universe heating in $R^2$-modified gravity is considered. The rates of particle production by the scalaron are calculated for different decay channels. Freezing of massive stable relics with the interaction strength typical for…
Superheavy dark matter can satisfy the observed dark matter abundance if the stability condition is fulfilled. Here, we propose a new Abelian gauge symmetry ${\rm U(1)}_H$ for the stability of superheavy dark matter as the electromagnetic…
We investigate the viability of a simple dark matter (DM) model consisting of a single fermion in the context of galactic dynamics. We use a consistent approach that does not presume a particular DM density profile but instead requires that…
In this thesis a simple extension of the Standard Model has been investigated. The Standard Model gauge group has been extended by an additional $U(1)_X$ group. The model introduces a new Higgs particle as well as three particles (a gauge…
The Standard Model of Particle Physics has proven to be tremendously successful as the fundamental theory that describes the elementary particles that compose our Universe, as well as the interactions among them. Despite the countless…
The nature of dark matter is one of the most pressing questions in particle physics. Yet all our present knowledge of the dark sector to date comes from its gravitational interactions with astrophysical systems. Moreover, astronomical…
One of the major challenges of modern physics is to decipher the nature of dark matter. Astrophysical observations provide ample evidence for the existence of an invisible and dominant mass component in the observable universe, from the…
Dark and baryonic matter contribute comparable energy density to the present Universe. The dark matter may also be responsible for the cosmic positron/electron excesses. We connect these phenomena with Dirac seesaw for neutrino masses. In…
Solar, atmospheric and reactor neutrino experiments established that neutrinos are massive. It is quite natural then to consider neutrinos as candidate particles for explaining the dark matter in halos around galaxies. We study the…
Dark matter is a fundamental constituent of the universe, which is needed to explain a wide variety of astrophysical and cosmological observations. Although the existence of dark matter was first postulated nearly a century ago and its…
We argue that primordial dark matter halos could be generated during radiation domination by long range attractive forces stronger than gravity. In this paper we derive the conditions under which these structures could dominate the dark…
The pervasive presence in space of a flux of high-speed, electrically uncharged dark matter particles is examined here for potential consequences. Dark matter interactions with ordinary matter are considered, and a model of the dark matter…