Primordial Nucleosynthesis for the New Cosmology: Determining Uncertainties and Examining Concordance

Big bang nucleosynthesis (BBN) and the cosmic microwave background (CMB) have a long history together in the standard cosmology. The general concordance between the predicted and observed light element abundances provides a direct probe of the universal baryon density. Recent CMB anisotropy measurements, particularly the observations performed by the WMAP satellite, examine this concordance by independently measuring the cosmic baryon density. Key to this test of concordance is a quantitative understanding of the uncertainties in the BBN light element abundance predictions. These uncertainties are dominated by systematic errors in nuclear cross sections. We critically analyze the cross section data, producing representations that describe this data and its uncertainties, taking into account the correlations among data, and explicitly treating the systematic errors between data sets. Using these updated nuclear inputs, we compute the new BBN abundance predictions, and quantitatively examine their concordance with observations. Depending on what deuterium observations are adopted, one gets the following constraints on the baryon density: OmegaBh^2=0.0229\pm0.0013 or OmegaBh^2 = 0.0216^{+0.0020}_{-0.0021} at 68% confidence, fixing N_{\nu,eff}=3.0. Concerns over systematics in helium and lithium observations limit the confidence constraints based on this data provide. With new nuclear cross section data, light element abundance observations and the ever increasing resolution of the CMB anisotropy, tighter constraints can be placed on nuclear and particle astrophysics. ABRIDGEDComment: 54 pages, 20 figures, 5 tables v2: reflects PRD version minor changes to text and reference

Generation of low-order harmonics in laser ablation plasmas

The third and fifth harmonics of a pulsed infrared laser (1064nm) delivering pulses of nanosecond duration have been generated in the laser ablation plasmas of various materials including the metals Al and Fe and the highly ionic insulators MgF 2 and NaCl. The harmonics were generated in a process triggered by laser ablation followed by frequency up-conversion of the fundamental laser beam that propagates parallel to the target surface. The spatial and temporal behaviour of the harmonics reveals the distinctive composition and dynamics of each plasma, gives insight into the species that act as nonlinear media and allows a comparison of different processes that control the generation efficiency. Low-order harmonic generation thus emerges as a powerful and universal technique for monitoring and diagnostics of ablation plasmas, and the results presented serve to guide the choice of solid materials for efficient high harmonic generation using ultrashort pulses in the femtosecond regime.Funding was provided by the Ministry of Science and Innovation of Spain (MICINN) under project CTQ2010- 15680. M.O. and M.S. acknowledge CONSOLIDER CSD2007-00058 and CAM (Geomateriales P2009/MAT 1629), respectively, for contracts. M.L.-A. thanks CSIC for a JAE-Pre contract.Peer Reviewe