971 research outputs found

    Appearance of quark-hadron duality in the Rein-Sehgal model

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    Quark-hadron duality in neutrino-nucleon reactions is investigated under the assumption that cross sections in the resonance region are given by the Rein-Sehgal model. The quantitative analysis of the duality is done by means of appropriate integrals of the structure functions in the Nachtmann variable. We conclude that with the definition of the resonance region W∈(M+mπ,2W\in (M+m_{\pi}, 2 GeV) the duality holds for neutrino-proton reaction F2F_2 structure function for Q2∈(0.5,3)Q^2\in (0.5, 3) GeV2^2 and it is absent for neutrino-neutron reaction.Comment: 4 pages, 7 figures, presented at NuInt05 conference, Okayama, Sept. 26-29, 200

    Spectral functions for medium-sized nuclei

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    The spectral functions for calcium and argon are constructed. It is verified that their predictions for the quasielastic electron-nucleus cross sections in the energy range ~1 GeV agree with the data. The argon spectral function is then used to obtain the quasielastic neutrino-nucleus cross section.Comment: 3 pages, 3 figures, presented at 5th International Workshop on Neutrino-Nucleus Interactions in the Few-GeV Region (NuInt07), Fermilab, USA, 30.05-3.06.200

    Theory of STM junctions for \pi-conjugated molecules on thin insulating films

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    A microscopic theory of the transport in a scanning tunnelling microscope (STM) set-up is introduced for \pi-conjugated molecules on insulating films, based on the density matrix formalism. A key role is played in the theory by the energy dependent tunnelling rates which account for the coupling of the molecule to the tip and to the substrate. In particular, we analyze how the geometrical differences between the localized tip and extended substrate are encoded in the tunnelling rate and influence the transport characteristics. Finally, using benzene as an example of a planar, rotationally symmetric molecule, we calculate the STM current voltage characteristics and current maps and analyze them in terms of few relevant angular momentum channels.Comment: 19 pages, 12 figures, minor changes to conform to published versio
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