889 research outputs found

    Heavy Quark Production in the Semihard QCD Approach at HERA and Beyond

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    Processes of heavy quark production at HERA, TEVATRON and THERA energies are considered using the semihard (kTk_T factorization) QCD approach with emphasis on the BFKL dynamics of gluon distributions.Comment: 4 pages, 5 figures, To appear in Proceedings of the 9th International Workshop on Deep Inelastic Scattering (DIS2001), Bologna, Italy, 27 Apr. - 1 May 200

    TMD PDFs in Drell-Yan lepton pair production at LHC

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    We consider the transverse momentum dependent (TMD) quark densities of the proton which are very important ingredients for unpolarized Drell-Yan (DY) lepton pair production. We calculate the TMD sea quark density as a convolution of the Catani-Ciafaloni-Fiorani-Marchesini (CCFM)-evolved gluon distribution and the TMD gluon-to-quark splitting function. Based on the O(α2){\cal O}(\alpha^2) production amplitude q∗+qˉ∗→Z/γ∗→l++l−q^* + \bar q^* \to Z/\gamma^* \to l^+ + l^-, calculated by taking into account the effective q∗qˉ∗Z/γ∗q^*\bar q^* Z/\gamma^* - vertex, we analyze the distributions on the dilepton invariant mass, transverse momentum and rapidity and specific angular correlations between the produced leptons as measured by the CMS, ATLAS and LHCb collaborations. We briefly duscuss also the process of assiciated lepton pair and jet production in pppp collisions at the LHC.Comment: Talk presented at International Workshop on Diffraction in High-Energy Physics, Diffraction-201

    Prompt charmonia production and polarization at LHC in the NRQCD with kt-factorization. Part I: psi(2S) meson

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    In the framework of kt-factorization approach, the production and polarization of prompt psi(2S) mesons in pp collisions at the LHC energies is studied. Our consideration is based on the non-relativistic QCD formalism for bound states and off-shell amplitudes for hard partonic subprocesses. The transverse momentum dependent (unintegrated) gluon densities in a proton were derived from Ciafaloni-Catani-Fiorani-Marchesini evolution equation or, alternatively, were chosen in accordance with Kimber-Martin-Ryskin prescription. The non-perturbative color-octet matrix elements were first deduced from the fits to the latest CMS data on psi(2S) transverse momentum distributions and then applied to describe the ATLAS and LHCb data on psi(2S) production and polarization at 7 TeV. We perform the estimation of polarization parameters λθ\lambda_\theta, λϕ\lambda_\phi and λθϕ\lambda_{\theta \phi} which determine psi(2S) spin density matrix and demonstrate that taking into account the off-shellness of initial gluons in the color-octet contributions leads to unpolarized psi(2S) production at high transverse momenta, that is in qualitative agreement with the LHC data.Comment: 19 pages, 8 figures. arXiv admin note: text overlap with arXiv:1108.285

    One-dimensional conduction in Charge-Density Wave nanowires

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    We report a systematic study of the transport properties of coupled one-dimensional metallic chains as a function of the number of parallel chains. When the number of parallel chains is less than 2000, the transport properties show power-law behavior on temperature and voltage, characteristic for one-dimensional systems.Comment: 4 pages, 5 figures, submitted to Phys. Rev. Let
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