Hard pomeron enhancement of ultrahigh-energy neutrino-nucleon cross-sections

An unknown small-x behavior of nucleon structure functions gives appreciable uncertainties to high-energy neutrino-nucleon cross-sections. We construct structure functions using at small x Regge inspired description by A. Donnachie and P. V. Landshoff with soft and hard pomerons, and employing at larger x the perturbative QCD expressions. The smooth interpolation between two regimes for each Q^2 is provided with the help of simple polynomial functions. To obtain low-x neutrino-nucleon structure functions $F_2^{\nu N, \bar \nu N}(x,Q^2)$ and singlet part of $F_{3}^{\nu N,\bar \nu N}(x,Q^2)$ from Donnachie-Landshoff function $F_2^{ep}(x,Q^2)$, we use the Q^2-dependent ratios R_2(Q^2) and R_3(Q^2) derived from perturbative QCD calculations. Non-singlet part of F_3 at low x, which is very small, is taken as power-law extrapolation of perturbative function at larger x. This procedure gives a full set of smooth neutrino-nucleon structure functions in the whole range of x and Q^2 at interest. Using these structure functions, we have calculated the neutrino-nucleon cross-sections and compared them with some other cross-sections known in literature. Our cross-sections turn out to be the highest among them at the highest energies, which is explained by contribution of the hard pomeron.Comment: Final revised version, accepted by Phys. Rev. D; 18 pages, 7 figure

The unique hybrid precipitate in a peak-aged Al-Cu-Mg-Ag alloy

The prevalent hardening phase forming in an Al-Cu-Mg-Ag alloy after peak-aging at 150 and 190 °C has been investigated using transmission electron microscopy methods. The precipitate atomic structure was determined. It is a hybrid precipitate (HP) with plate morphology on {111}Al planes, consisting of orthorhombic and hexagonal structural fragments. Density functional theory calculations suggest that the hybridization reduces structural incompatibility of the HP plates with the Al matrix at the broad interfacial boundaries. Incorporation of Cu, Mg and Ag in the bulk HP structure reduces its formation enthalpy.acceptedVersio