411 research outputs found

    Interannual and seasonal variability of atmospheric inhomogeneities from satellite systems data and it's correlation with atmosphere monitoring

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    © 2016 SPIE.In this paper we presented results long-term experimental study of atmosphere remote sensing by GPS-GLONASS signals and simultaneous near surface atmospheric parameters measurements in Kazan city. During the period of 2010 - 2012. The interannual and seasonal variability of the radiovawes zenith tropospheric delay structure functions was analyzed. The correlation coefficient of the of the time structure function decimeter radio waves zenith tropospheric delay power approximation with surface temperature reaches a value of 0.73 for the fluctuations with time scales up to 8 hours. According to the results it can be assume a strong influence of the synoptic processes and the underlying surface on the formation of mesoscale fluctuations in the satellite navigation systems phase path

    Capture of particles of dust by convective flow

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    Interaction of particles of dust with vortex convective flows is under theoretical consideration. It is assumed that the volume fraction of solid phase is small, variations of density due to nonuniform distribution of particles and those caused by temperature nonisothermality of medium are comparable. Equations for the description of thermal buoyancy convection of a dusty medium are developed in the framework of the generalized Boussinesq approximation taking into account finite velocity of particle sedimentation. The capture of a cloud of dust particles by a vortex convective flow is considered, general criterion for the formation of such a cloud is obtained. The peculiarities of a steady state in the form of a dust cloud and backward influence of the solid phase on the carrier flow are studied in detail for a vertical layer heated from the sidewalls. It is shown that in the case, when this backward influence is essential, a hysteresis behavior is possible. The stability analysis of the steady state is performed. It turns out that there is a narrow range of governing parameters, in which such a steady state is stable.Comment: 14 pages, 10 figures, published in Physics of Fluid

    Modeling of radiative - conductive heat transfer in compositing materials

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    A layer of composite material is investigated, which is heated one-sidedly with one-dimensional energy transfer accounting for thermal conductivity and radiation. A mathematical model is suggested for non-stationary coefficient thermophysical problem under radiative-conductive heat transfer in a material layer. Temperature dependencies of thermal capacity and thermal conductivity coefficient of composite radio-transparent material have been determined through numerical modeling by solving the coefficient reverse problem of thermal conductivity

    Measurement of neutral current e+/-p cross sections at high Bjorken x with the ZEUS detector

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    The neutral current e+/-p cross section has been measured up to values of Bjorken x of approximately 1 with the ZEUS detector at HERA using an integrated luminosity of 187 inv. pb of e-p and 142 inv. pb of e+p collisions at sqrt(s) = 318GeV. Differential cross sections in x and Q2, the exchanged boson virtuality, are presented for Q2 geq 725GeV2. An improved reconstruction method and greatly increased amount of data allows a finer binning in the high-x region of the neutral current cross section and leads to a measurement with much improved precision compared to a similar earlier analysis. The measurements are compared to Standard Model expectations based on a variety of recent parton distribution functions.Comment: 39 pages, 9 figure

    Measurement of the cross-section ratio sigma_{psi(2S)}/sigma_{J/psi(1S)} in deep inelastic exclusive ep scattering at HERA

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    The exclusive deep inelastic electroproduction of ψ(2S)\psi(2S) and J/ψ(1S)J/\psi(1S) at an epep centre-of-mass energy of 317 GeV has been studied with the ZEUS detector at HERA in the kinematic range 2<Q2<802 < Q^2 < 80 GeV2^2, 30<W<21030 < W < 210 GeV and t<1|t| < 1 GeV2^2, where Q2Q^2 is the photon virtuality, WW is the photon-proton centre-of-mass energy and tt is the squared four-momentum transfer at the proton vertex. The data for 2<Q2<52 < Q^2 < 5 GeV2^2 were taken in the HERA I running period and correspond to an integrated luminosity of 114 pb1^{-1}. The data for 5<Q2<805 < Q^2 < 80 GeV2^2 are from both HERA I and HERA II periods and correspond to an integrated luminosity of 468 pb1^{-1}. The decay modes analysed were μ+μ\mu^+\mu^- and J/ψ(1S)π+πJ/\psi(1S) \,\pi^+\pi^- for the ψ(2S)\psi(2S) and μ+μ\mu^+\mu^- for the J/ψ(1S)J/\psi(1S). The cross-section ratio σψ(2S)/σJ/ψ(1S)\sigma_{\psi(2S)}/\sigma_{J/\psi(1S)} has been measured as a function of Q2,WQ^2, W and tt. The results are compared to predictions of QCD-inspired models of exclusive vector-meson production.Comment: 24 pages, 8 figure

    Combined QCD and electroweak analysis of HERA data

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    A simultaneous fit of parton distribution functions (PDFs) and electroweak parameters to HERA data on deep inelastic scattering is presented. The input data are the neutral current and charged current inclusive cross sections which were previously used in the QCD analysis leading to the HERAPDF2.0 PDFs. In addition, the polarisation of the electron beam was taken into account for the ZEUS data recorded between 2004 and 2007. Results on the vector and axial-vector couplings of the Z boson to u- and d-type quarks, on the value of the electroweak mixing angle and the mass of the W boson are presented. The values obtained for the electroweak parameters are in agreement with Standard Model predictions.Comment: 32 pages, 10 figures, accepted by Phys. Rev. D. Small corrections from proofing process and small change to Fig. 12 and Table

    Limits on the effective quark radius from inclusive epep scattering at HERA

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    The high-precision HERA data allows searches up to TeV scales for Beyond the Standard Model contributions to electron-quark scattering. Combined measurements of the inclusive deep inelastic cross sections in neutral and charged current epep scattering corresponding to a luminosity of around 1 fb1^{-1} have been used in this analysis. A new approach to the beyond the Standard Model analysis of the inclusive epep data is presented; simultaneous fits of parton distribution functions together with contributions of "new physics" processes were performed. Results are presented considering a finite radius of quarks within the quark form-factor model. The resulting 95% C.L. upper limit on the effective quark radius is 0.4310160.43\cdot 10^{-16} cm.Comment: 10 pages, 4 figures, accepted by Phys. Lett.

    Search for a narrow baryonic state decaying to pKS0{pK^0_S} and pˉKS0{\bar{p}K^0_S} in deep inelastic scattering at HERA

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    A search for a narrow baryonic state in the pKS0pK^0_S and pˉKS0\bar{p}K^0_S system has been performed in epep collisions at HERA with the ZEUS detector using an integrated luminosity of 358 pb1^{-1} taken in 2003-2007. The search was performed with deep inelastic scattering events at an epep centre-of-mass energy of 318 GeV for exchanged photon virtuality, Q2Q^2, between 20 and 100 GeV2\rm{} GeV^{2}. Contrary to evidence presented for such a state around 1.52 GeV in a previous ZEUS analysis using a sample of 121 pb1^{-1} taken in 1996-2000, no resonance peak was found in the p(pˉ)KS0p(\bar{p})K^0_S invariant-mass distribution in the range 1.45-1.7 GeV. Upper limits on the production cross section are set.Comment: 16 pages, 4 figures, accepted by Phys. Lett. B. Minor changes from journal reviewing process, including a small correction to figure

    Challenges in QCD matter physics - The Compressed Baryonic Matter experiment at FAIR

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    Substantial experimental and theoretical efforts worldwide are devoted to explore the phase diagram of strongly interacting matter. At LHC and top RHIC energies, QCD matter is studied at very high temperatures and nearly vanishing net-baryon densities. There is evidence that a Quark-Gluon-Plasma (QGP) was created at experiments at RHIC and LHC. The transition from the QGP back to the hadron gas is found to be a smooth cross over. For larger net-baryon densities and lower temperatures, it is expected that the QCD phase diagram exhibits a rich structure, such as a first-order phase transition between hadronic and partonic matter which terminates in a critical point, or exotic phases like quarkyonic matter. The discovery of these landmarks would be a breakthrough in our understanding of the strong interaction and is therefore in the focus of various high-energy heavy-ion research programs. The Compressed Baryonic Matter (CBM) experiment at FAIR will play a unique role in the exploration of the QCD phase diagram in the region of high net-baryon densities, because it is designed to run at unprecedented interaction rates. High-rate operation is the key prerequisite for high-precision measurements of multi-differential observables and of rare diagnostic probes which are sensitive to the dense phase of the nuclear fireball. The goal of the CBM experiment at SIS100 (sqrt(s_NN) = 2.7 - 4.9 GeV) is to discover fundamental properties of QCD matter: the phase structure at large baryon-chemical potentials (mu_B > 500 MeV), effects of chiral symmetry, and the equation-of-state at high density as it is expected to occur in the core of neutron stars. In this article, we review the motivation for and the physics programme of CBM, including activities before the start of data taking in 2022, in the context of the worldwide efforts to explore high-density QCD matter.Comment: 15 pages, 11 figures. Published in European Physical Journal
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