The impact on cosmology of a primordial scaling field

A scalar field with an exponential potential has the particular property that it is attracted into a solution in which its energy scales as the dominant component (radiation or matter) of the Universe, contributing a fixed fraction of the total energy density. We briefly discuss the dynamics of such a scalar field and its impact on Big Bang nucleosynthesis, the growth of large scale structure and abundance of damped Lyman$-\alpha$ systems at high redshift. Given the simplicity of the model, its theoretical motivation, and its success in matching observations, we argue that it should be taken on par with other currently viable models of structure formation.Comment: 3 pages, uses prcrc.sty, 2 figures, to be published in proceedings of Dark Matter '9

Skinning the Cat: Education Distribution, Changes in the School Premium and Earnings Inequality

This paper applies the procedure in JUHN ET ALL (1993) to decompose changes in income inequality over time in terms of education-related causal factors: school premiums, educational distribution and residual changes. The main conclusion is that reductions in the school premiums have systematically had a negative impact on income inequality during the last twenty years. At the same time, education has become more unequally distributed for individuals below the median labor income level and more equally distributed for those above it. The combination of the two forces has reduced income dispersion for the top half of earners, and slightly increased it among the bottom half. This difference in trends of educational distribution lies behind an apparently stable profile of income inequality (considering the whole earnings distribution).

Pension Reform in Brazil: Transitional Issues in a Model with Endogenous Labor Supply

Brazilian PAYG system has been under financial stress and needs to be reformed. I use a computational general equilibrium model, with 55 overlapping generations to simulate macroeconomic and welfare impacts of alternative social security reforms. Transition turns out to have quite different redistributional effects for the generations involved depending on which tax is used to finance it. Under a variety of possible transitional schemes, there is no tax path that is strictly preferred by every generation.Social Security, Welfare, General Equilibrium, Macroeconomics, Overlapping Generation

Nonperturbative QCD treatment of J/ψJ/\psi photoproduction

We present a nonperturbative QCD calculation of elastic $J/\psi$ meson production in photon-proton scattering at high energies. Using light cone wave functions of the photon and vector mesons, and the framework of the model of the stochastic QCD vacuum, we calculate the differential and integrated elastic cross sections for \gamma p \goto J/\psi p . With an energy dependence following the two-pomeron model we are able to give a consistent description of the integrated cross sections and the differential cross sections at low $|t|$ in the range from 20 GeV up to the highest HERA energies. We discuss different approaches to introduce saturation and find no specific effects up to energies presently available. We also calculate and compare to experiments the cross section for $\upsilon$ photoproduction.Comment: 24 pages, 10 figures, 4 table

Note on Shadowing and Diffraction in Deep-Inelastic Lepton Scattering

We discuss the close relation between shadowing in deep-inelastic lepton-nucleus scattering and diffractive photo- and leptoproduction of hadrons from free nucleons. We show that the magnitude of nuclear shadowing at small Bjorken-x, as measured by the E665 and NMC collaborations, is directly related to HERA data on the amount of diffraction in the scattering from free nucleons.Comment: 6 pages, Latex, to be published in Eur. Phys. J.