Primordial Nucleosynthesis, Cosmic Microwave Background and Neutrinos

We report the results of a recent likelihood analysis combining the primordial nucleosynthesis and the BOOMERanG and MAXIMA-1 data on cosmic microwave background radiation anisotropies. We discuss the possible implications for relic neutrino background of a high value for the baryonic matter content of the universe, larger than what is expected in a standard nucleosynthesis scenario.Comment: 3 pages, 1 figure, some typos corrected, one reference added, presented by G. Mangano at NOW 2000, Europhysics Neutrino Oscillation Workshop, Otranto 200

Ultrahigh energy neutrinos with a mediterranean neutrino telescope

A study of the ultra high energy neutrino detection performances of a km^3 Neutrino Telescope sitting at the three proposed sites for "ANTARES", "NEMO" and "NESTOR" in the Mediterranean sea is here performed. The detected charged leptons energy spectra, entangled with their arrival directions, provide an unique tool to both determine the neutrino flux and the neutrino-nucleon cross section.Comment: 10 pages, 10 figures, Proceedings of XII International Workshop on Neutrino Telescopes, Venezia 200

Fermion Mass Matrices in term of the Cabibbo-Kobayashi-Maskawa Matrix and Mass Eigenvalues

A parameter free, model independent analysis of quark mass matrices is carried out. We find a representation in terms of a diagonal mass matrix for the down (up) quarks and a suitable matrix for the up (down) quarks, such that the mass parameters only depend on the six quark masses and the three angles and phase appearing in the Cabibbo-Kobayashi-Maskawa matrix. The results found may also be applied to the Dirac mass matrices of the leptons.Comment: 7 pages LaTeX, no figures. Title changed, Particle Data Group parametrization of CKM matrix used in equation (8), numerical values in table 1 evaluated using the quark mass values at the Z^o mass scale, equation (21) eliminated and 2 references change

The standard and degenerate primordial nucleosynthesis versus recent experimental data

We report the results on Big Bang Nucleosynthesis (BBN) based on an updated code, with accuracy of the order of 0.1% on He4 abundance, compared with the predictions of other recent similar analysis. We discuss the compatibility of the theoretical results, for vanishing neutrino chemical potentials, with the observational data. Bounds on the number of relativistic neutrinos and baryon abundance are obtained by a likelihood analysis. We also analyze the effect of large neutrino chemical potentials on primordial nucleosynthesis, motivated by the recent results on the Cosmic Microwave Background Radiation spectrum. The BBN exclusion plots for electron neutrino chemical potential and the effective number of relativistic neutrinos are reported. We find that the standard BBN seems to be only marginally in agreement with the recent BOOMERANG and MAXIMA-1 results, while the agreement is much better for degenerate BBN scenarios for large effective number of neutrinos, N_\nu \sim 10.Comment: LaTeX2e, 41 pages, 20 figures. Minor changes and 4 figures slightly modifie

The α+d→ 6Li+γ\alpha + d \rightarrow ~ ^6\mathrm{Li} + \gamma astrophysical SS-factor and its implications for Big Bang Nucleosynthesis

The \alpha+d\rightarrow\, ^6{\rm Li}+\gamma radiative capture is studied in order to predict the $^6$Li primordial abundance. Within a two-body framework, the $\alpha$ particle and the deuteron are considered the structureless constituents of $^6$Li. Five $\alpha+d$ potentials are used to solve the two-body problem: four of them are taken from the literature, only one having also a tensor component. A fifth model is here constructed in order to reproduce, besides the $^6$Li static properties as binding energy, magnetic dipole and electric quadrupole moments, also the $S$-state asymptotic normalization coefficient (ANC). The two-body bound and scattering problem is solved with different techniques, in order to minimize the numerical uncertainty of the present results. The long-wavelength approximation is used, and therefore only the electric dipole and quadrupole operators are retained. The astrophysical $S$-factor is found to be significantly sensitive to the ANC, but in all the cases in good agreement with the available experimental data. The theoretical uncertainty has been estimated of the order of few % when the potentials which reproduce the ANC are considered, but increases up to $\simeq 20$ % when all the five potential models are retained. The effect of this $S$-factor prediction on the $^6$Li primordial abundance is studied, using the public code PArthENoPE. For the five models considered here we find $^6{\rm Li}/$H$= (0.9 - 1.8) \times 10^{-14}$, with the baryon density parameter in the 3-$\sigma$ range of Planck 2015 analysis, $\Omega_b h^2= 0.02226 \pm 0.00023$.Comment: 26 pages, 9 figure

A Positive Test for Fermi-Dirac Distributions of Quark-Partons

By describing a large class of deep inelastic processes with standard parameterization for the different parton species, we check the characteristic relationship dictated by Pauli principle: broader shapes for higher first moments. Indeed, the ratios between the second and the first moment and the one between the third and the second moment for the valence partons is an increasing function of the first moment and agrees quantitatively with the values found with Fermi-Dirac distributions.Comment: 15 pages LaTeX, 2 eps figures. Final version, to appear in Mod. Phys. Lett.

Constraining neutrino physics with BBN and CMBR

We perform a likelihood analysis of the recent results on the anisotropy of Cosmic Microwave Background Radiation from the BOOMERanG and DASI experiments to show that they single out an effective number of neutrinos in good agreement with standard Big Bang Nucleosynthesis. We also consider degenerate Big Bang Nucleosynthesis to provide new bounds on effective relativistic degrees of freedom $N_\nu$ and, in particular, on neutrino chemical potential $\xi_\alpha$. When including Supernova Ia data we find, at $2\sigma$, $N_\nu \leq 7$ and $-0.01 \leq \xi_e \leq 0.22$, $|\xi_{\mu,\tau}|\leq 2.6$.Comment: 6 pages, 3 figures, some reference adde

Primordial Nucleosynthesis: from precision cosmology to fundamental physics

We present an up-to-date review of Big Bang Nucleosynthesis (BBN). We discuss the main improvements which have been achieved in the past two decades on the overall theoretical framework, summarize the impact of new experimental results on nuclear reaction rates, and critically re-examine the astrophysical determinations of light nuclei abundances. We report then on how BBN can be used as a powerful test of new physics, constraining a wide range of ideas and theoretical models of fundamental interactions beyond the standard model of strong and electroweak forces and Einstein's general relativity.Comment: 148 pages, 66 figures, revised version accepted by Physics Report