Overproduction of primordial helium-4 in the presence of neutrino oscillations

The maximum overproduction of helium-4 in cosmological nucleosynthesis with active--sterile neutrino oscillations, nu_e -> nu_s, efficient after decoupling of electron neutrino, is analyzed. The kinetic effects on primordial nucleosynthesis due to neutrino spectrum distortion, caused by oscillations, are precisely taken into account. The maximum overproduction of primordial He-4 as a function of oscillation parameters is obtained from the analysis of the kinetics of the nucleons and the oscillating neutrinos, for the full range of parameters of the discussed oscillation model. A maximum relative increase of He-4, up to 14% for non-resonant oscillations and up to 32% for resonant ones is registered. Cosmological constraints on oscillation parameters are also discussed.Comment: 17 pages, 5 figures, much extended version, references and 3 figures adde

BARYOGENESIS MODEL SUGGESTING ANTIGALAXIES

Abstract A non-GUT baryogenesis model, according to which our Universe may contain clusters of antigalaxies is discussed. A mechanism of separation of vast quantities of matter from such of antimatter is described. The provided analysis showed that for a natural range of model parameters a sufficient separation between matter and antimatter regions, required from observational data, can be obtained

Neutrino Oscillations and the Early Universe

The observational and theoretical status of neutrino oscillations in connection with solar and atmospheric neutrino anomalies is presented in brief. The effect of neutrino oscillations on the early Universe evolution is discussed in detail. A short review is given of the standard Big Bang Nucleosynthesis and the influence of resonant and nonresonant neutrino oscillations on active neutrinos and on primordial nucleosynthesis of He-4. BBN cosmological constraints on neutrino oscillation parameters are discussed.Comment: 21 p., 6 figures, a review based on raview talk at NCYA Conference and a presentation at CAPP200

Further studies on relic neutrino asymmetry generation I: the adiabatic Boltzmann limit, non-adiabatic evolution, and the classical harmonic oscillator analogue of the quantum kinetic equations

We demonstrate that the relic neutrino asymmetry evolution equation derived from the quantum kinetic equations (QKEs) reduces to the Boltzmann limit that is dependent only on the instantaneous neutrino number densities, in the adiabatic limit in conjunction with sufficient damping. An original physical and/or geometrical interpretation of the adiabatic approximation is given, which serves as a convenient visual aid to understanding the sharply contrasting resonance behaviours exhibited by the neutrino ensemble in opposing collision regimes. We also present a classical analogue for the evolution of the difference in $\nu_{\alpha}$ and $\nu_s$ number densities which, in the Boltzmann limit, is akin to the behaviour of the generic reaction $A \rightleftharpoons B$ with equal forward and reverse reaction rate constants. A new characteristic quantity, the matter and collision-affected mixing angle of the neutrino ensemble, is identified here for the first time. The role of collisions is revealed to be twofold: (i) to wipe out the inherent oscillations, and (ii) to equilibrate the $\nu_{\alpha}$ and $\nu_s$ number densities in the long run. Studies on non-adiabatic evolution and its possible relation to rapid oscillations in lepton number generation also feature, with the introduction of an adiabaticity parameter for collision-affected oscillations.Comment: RevTeX, 38 pages including 8 embedded figure

Applications of Abundance Data and Requirements for Cosmochemical Modeling

Understanding the evolution of the universe from Big Bang to its present state requires an understanding of the evolution of the abundances of the elements and isotopes in galaxies, stars, the interstellar medium, the Sun and the heliosphere, planets and meteorites. Processes that change the state of the universe include Big Bang nucleosynthesis, star formation and stellar nucleosynthesis, galactic chemical evolution, propagation of cosmic rays, spallation, ionization and particle transport of interstellar material, formation of the solar system, solar wind emission and its fractionation (FIP/FIT effect), mixing processes in stellar interiors, condensation of material and subsequent geochemical fractionation. Here, we attempt to compile some major issues in cosmochemistry that can be addressed with a better knowledge of the respective element or isotope abundances. Present and future missions such as Genesis, Stardust, Interstellar Pathfinder, and Interstellar Probe, improvements of remote sensing instrumentation and experiments on extraterrestrial material such as meteorites, presolar grains, and lunar or returned planetary or cometary samples will result in an improved database of elemental and isotopic abundances. This includes the primordial abundances of D, ^3He, ^4He, and ^7Li, abundances of the heavier elements in stars and galaxies, the composition of the interstellar medium, solar wind and comets as well as the (highly) volatile elements in the solar system such as helium, nitrogen, oxygen or xenon