Neutrinos and Big-Bang Nucleosynthesis

Observations of clusters and super clusters of galaxies have indicated that the Universe is more dominated by baryons than ever estimated in the homogeneous cosmological model for primordial nucleosynthesis. Recent detections of possibly low deuterium abundance in Lyman-$\alpha$ clouds along the line of sight to high red-shift quasars have raised another potential difficulty that \he4 is overproduced in any cosmological models which satisfy the low deuterium abundance constraint. We show that the inhomogeneous cosmological model with degenerate electron-neutrino can resolve these two difficulties.Comment: 7 pages, latex, 3 figures. To appear in Nucl. Phys. A62

Modeling Liquid Water Content of Atmospheric Aerosols

The contribution of liquid water to measure aerosol was assessed using a numerical approach for European measurement data. Aerosol mass is usually determined after conditioning of the filter under dry condition for a predefined period according to a standard procedure. However, we find that the equilibrium of aerosol is not fully established and water is not completely evaporated after the conditioning. In order to estimate the aerosol humidity, a mass transfer coefficient was derived for evaporating from filters. DAta from actual measurements of aerosol humidity were applied with a numerical kinetic approach, using the thermodynamic equilibrium as a boundary condition. The calculated coefficient ranges from 10-5 to 10-4 with an average value of 10-4.49. Using this average value the expected water content of aerosol was assessed for a site in Austria. In a data set covering one year with daily samples, water contributed to the total amss between 0.00 percent and 35.9 percent with an average value of 4.1 percent. Most of the samples contained between one and two percent water, according to the calculations. In winter the air is humid and the concentration of inorganic hygroscopic compunds is also high, and so the amount of water uptake from the air is high. Under such conditions more than half of unidentified components is considered to be water. In summer the amount of hygroscopic components as well as relative humidity is low, water then yields only 8.8 percent of unidentifiedcomponents. According to the model calculations, it takes about 30 hours on annula average until 95 percent of the initial amount of water uptake is evaporated on the filter and even longer in winter. The average water content at 49 sites of EMEP in 1999 after conditioning for 48 hours ranges from 0.54 ug m-3 to 3.8 ug m-3, that is 2.6 percent to 18.2 percent to total aerosol mass, while the mass trnasfer coefficient varies from 10-4 to 10-5

Meson Synchrotron Emission from Central Engines of Gamma-Ray Bursts with Strong Magnetic Fields

Gamma-ray bursts (GRBs) are presumed to be powered by still unknown central engines for the timescales in the range $1ms \sim$ a few s. We propose that the GRB central engines would be a viable site for strong meson synchrotron emission if they were the compact astrophysical objects such as neutron stars or rotating black holes with extremely strong magnetic fields $H \sim10^{12} - 10^{17}G$ and if protons or heavy nuclei were accelerated to ultra-relativistic energies of order $\sim 10^{12}-10^{22}eV$. We show that the charged scalar mesons like $\pi^{\pm}$ and heavy vector mesons like $\rho$, which have several decay modes onto $\pi^{\pm}$, could be emitted with high intensity a thousand times larger than photons through strong couplings to ultra-relativistic nucleons. These meson synchrotron emission processes eventually produce a burst of very high-energy cosmic neutrinos with $10^{12} eV \leq E_{\nu}$. These neutrinos are to be detected during the early time duration of short GRBs.Comment: 12 pages, 4 figures. Accepted for publication in the Astrophysical Journal Letter

Enhanced Heavy-Element Formation in Baryon-Inhomogeneous Big-Bang Models

We show that primordial nucleosynthesis in baryon inhomogeneous big-bang models can lead to significant heavy-element production while still satisfying all the light-element abundance constraints including the low lithium abundance observed in population II stars. The parameters which admit this solution arise naturally from the process of neutrino induced inflation of baryon inhomogeneities prior to the epoch of nucleosynthesis. These solutions entail a small fraction of baryons (\le 2\%) in very high density regions with local baryon-to-photon ratio $\eta^h\approx 10^{-4}$, while most baryons are at a baryon-to-photon ratio which optimizes the agreement with light-element abundances. The model would imply a unique signature of baryon inhomogeneities in the early universe, evidenced by the existence of primordial material containing heavy-element products of proton and alpha- burning reactions with an abundance of $[Z]\sim -6 to -4$.Comment: 19 pages in plain Tex, 5 figures (not included) available by fax or mail upon request, ApJ in press, L

Invariants of Collective Neutrino Oscillations

We consider the flavor evolution of a dense neutrino gas by taking into account both vacuum oscillations and self interactions of neutrinos. We examine the system from a many-body perspective as well as from the point of view of an effective one-body description formulated in terms of the neutrino polarization vectors. We show that, in the single angle approximation, both the many-body picture and the effective one-particle picture possess several constants of motion. We write down these constants of motion explicitly in terms of the neutrino isospin operators for the many-body case and in terms of the polarization vectors for the effective one-body case. The existence of these constants of motion is a direct consequence of the fact that the collective neutrino oscillation Hamiltonian belongs to the class of Gaudin Hamiltonians. This class of Hamiltonians also includes the (reduced) BCS pairing Hamiltonian describing superconductivity. We point out the similarity between the collective neutrino oscillation Hamiltonian and the BCS pairing Hamiltonian. The constants of motion manifest the exact solvability of the system. Borrowing the well established techniques of calculating the exact BCS spectrum, we present exact eigenstates and eigenvalues of both the many-body and the effective one-particle Hamiltonians describing the collective neutrino oscillations. For the effective one-body case, we show that spectral splits of neutrinos can be understood in terms of the adiabatic evolution of some quasi-particle degrees of freedom from a high density region where they coincide with flavor eigenstates to the vacuum where they coincide with mass eigenstates. We write down the most general consistency equations which should be satisfied by the effective one-body eigenstates and show that they reduce to the spectral split consistency equations for the appropriate initial conditions.Comment: 26 pages with one figure. Published versio