43,573 research outputs found

    On the condensed density of the generalized eigenvalues of pencils of Hankel Gaussian random matrices and applications

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    Pencils of Hankel matrices whose elements have a joint Gaussian distribution with nonzero mean and not identical covariance are considered. An approximation to the distribution of the squared modulus of their determinant is computed which allows to get a closed form approximation of the condensed density of the generalized eigenvalues of the pencils. Implications of this result for solving several moments problems are discussed and some numerical examples are provided.Comment: 30 pages, 16 figures, better approximations provide

    Leptoproduction of charm revisited

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    We calculate the energy--momentum distribution of the charmed quarks produced in neutrino reactions on protons, quantifying the importance of mass and current non--conservation effects. We study the strange and charm distributions probed in neutrino interactions in the presently accessible kinematical region. Some ambiguities inherent to the extraction of the parton densities from dimuon data are pointed out.Comment: 9 pages, DFTT 72/9

    Extracting the Strange Density from xF3xF_3

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    We present a QCD analysis of the strange and charm contributions to the neutrino deep inelastic structure function xF3xF_3. We show that next-to-leading order effects, which are relatively important for F2F_2, play a lesser role in the case of xF3xF_3. The neutrino--antineutrino difference xF3Μ−xF3ΜˉxF_3^{\nu} - xF_3^{\bar \nu} provides a new determination of the strange density, which exhibits some advantages with respect to other traditional methods.Comment: 12 page

    Phenomenology of SIDIS unpolarized cross sections and azimuthal asymmetries

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    I review the phenomenology of unpolarized cross sections and azimuthal asymmetries in semi-inclusive deeply inelastic scattering (SIDIS). The general theoretical framework is presented and the validity of the Gaussian model is discussed. A brief account of the existing analyses is provided.Comment: 12 pages, 5 figures, invited talk at "Transversity 2011", Veli Losinj, Croati

    Unitarization of Structure Functions at Large 1/x{\bf 1/x}

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    We discuss the effects of the ss-channel unitarization on the xx and Q2Q^{2} dependence of structure functions. The unitarization is implemented at the level of photoabsorption cross sections by resorting to the light--cone wave functions of virtual photons and to the diagonalization property of the scattering matrix in a basis of Fock states of the photon with fixed transverse size. Triple pomeron effects are also explicitly taken into account. We find large unitarity corrections to the structure functions at x<10−2x < 10^{-2}. The results are in very good agreement with the existing NMC and the preliminary HERA data.Comment: 12 page

    Understanding transversity: present and future

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    I review the present state of knowledge concerning transversity distributions and related observables. In particular, I discuss the phenomenology of transverse asymmetries in e p\uparrow, p p\uparrow, p\uparrow p\uparrow and pbar \uparrow p\uparrow scattering, and the perspectives of ongoing and future research.Comment: 9 pages, 1 figure, plenary talk at SPIN 2004 (Trieste), to be published in the Proceeding