680 research outputs found
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.
Diffractive rho^0 photo- and leptoproduction at high energies
We discuss the elastic photo- and leptoproduction of rho^0-mesons from
nucleons at Q^2 < 1 GeV^2 as studied in recent experiments at HERA and FNAL. We
find that the mass distribution of the measured \pi^+\pi^- pairs is determined
to a large extent by the two-pion contribution to the photon spectral function
as given by the pion form factor. With rising Q^2 the rate of diffractive
events decreases and the \pi^+\pi^- mass distribution approaches a symmetric
shape.Comment: 7 pages LaTeX, 3 figures, to appear in Phys.Lett.
Gluon- vs. Sea quark-Shadowing
We calculate the shadowing of sea quarks and gluons and show that the
shadowing of gluons is {\it not} simply given by the sea quark shadowing,
especially at small . The calculations are done in the lab frame approach by
using the generalized vector meson dominance model. Here the virtual photon
turns into a hadronic fluctuation long before the nucleus. The subsequent
coherent interaction with more than one nucleon in the nucleus leads to the
depletion known as shadowing. A
comparison of the shadowing of quarks to E665 data for and
shows good agreement.Comment: 9 pages, 3 eps figure
Reefs and Coral Carpets in the Miocene Paratethys (Badenian, Leitha Limestone, Austria)
Biohermal (reefs) and biostromal (coral carpets) facies were studied in the Austrian Middle Miocene Leitha Limestone. In the Vienna Basin ( Fenk quarry ) non-framebuilding and framebuilding biostromal coral communities were found. In the Styrian Basin, well developed patch reefs were observed besides coral carpets. In the Fenk quarry, 2 coral carpet types, four non-framework coral communities, and one bivalve/coral community were found. In Retznei quarry (Styrian Basin) patch reefs, basal corallinacean calcarenites were followed by a Ponies layer capped by marl, and the main reef-building higher diversity phase dominated by faviids ( Montastraea, Tarbellastraea). In the Tittenbacher quarry no internal zonation was observed in the patch reef. The differences between reef, coral carpet, and non-framebuilding coral communities are equivalent to those in Recent systems (e.g., Red Sea). Our study therefore provides clear evidence that coral bioherms and biostromes occurred as distinct systems in the past and the Recent
Sustainable product development strategies: Business planning and performance implications
Copyright © 2012 by Institution of Mechanical Engineers. This is the author's accepted manuscript. The final published article is available from the link below.Manufacturing firms are under many financial and competitive pressures which focus attention on the performance of their manufacturing processes. In this paper the opportunities for improving the environmental impact of products within the constraints of existing manufacturing infrastructure are examined. Approaches which support sustainability in two aspects are proposed, firstly, the provision of products to the users in ways which extend the product life and secondly, manufacturing approaches which reduce resource usage. This paper outlines three different sustainable development strategies for different product types and describes the cost implications for manufacturers across the life-cycle. The performance measures affected by these strategies are examined drawing on product development case studies from a number of high technology sectors to highlight the different approaches taken. The results are intended to aid manufacturers during the earliest stages of business planning to consider alternative product development approaches which are more sustainable
Deuteron Spin Structure Functions at Small Bjorken-x
We investigate polarized deuteron structure functions at small values of the
Bjorken variable, x < 0.1. In this region contributions from the coherent
interaction of diffractively excited hadronic states with both nucleons become
important. A proper treatment of this process requires an extension of the
Glauber-Gribov multiple scattering theory to include spin degrees of freedom.
In the kinematic domain of current fixed target experiments we observe that
shadowing effects in g_1d are approximately twice as large as for the
unpolarized structure function F_2d. Furthermore at x < 0.1 the tensor
structure function b_1 is found to receive significant contributions from
coherent double scattering.Comment: 30 pages, Revtex, include discussion on t-dependence of diffractive
production processes, to appear in Phys. Rev.
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