1,489 research outputs found

    Quarkonium production via recombination

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    The contrast between model predictions for the transverse momentum spectra of J/Psi observed in Au-Au collisions at RHIC is extended to include effects of nuclear absorption. We find that the difference between initial production and recombination is enhanced in the most central collisions. Models utilizing a combination of these sources may eventually be able to place constraints on their relative magnitudes.Comment: Based on invited plenary talk at the 2nd International Conference on Hard and Electromagnetic Probes of High-Energy Nuclear Collisions, Asilomar, CA, June 9-16, 2006, to be published in Nucl. Phys.

    Lambda polarization and single-spin left-right asymmetry in diffractive hadron-hadron collisions

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    We discuss Lambda polarization and single-spin left-right asymmetry in diffractive hadron-hadron scattering at high energies. We show that the physical picture proposed in a recent Letter is consistent with the experimental observation that Λ\Lambda polarization in the diffractive process, ppΛK+ppp\to \Lambda K^+p, is much higher than that in the inclusive reaction, ppΛXpp\to \Lambda X. We make predictions for the left-right asymmetry, A_N, and for the spin transfer, DNNΛD_{NN}^\Lambda, in the single-spin process p()pΛK+pp(\uparrow)p\to \Lambda K^+p and suggest further experimental tests of the proposed picture.Comment: 14 pages, 3 ps-figures. Phys. Rev. D (in press

    Hyperon polarization in semi-inclusive deeply inelastic lepton-nucleon scattering at high energy

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    We calculate the polarizations for different octet hyperons produced in the current fragmentation regions of the deeply inelastic lepton-nucleon scatterings μNμHX\mu^-N \to \mu^- HX and νμNμHX\nu_{\mu} N \to \mu^- HX at high energy using different models for spin transfer in fragmentation processes. The results show that measurements of those hyperon polarizations should provide useful information to distinguish between different models in particular the SU(6) and the DIS pictures used frequently in the literature. We found, in particular, that measuring the polarization of Σ+\Sigma^+ produced in these processes can give a better test to the validity of the different spin transfer models.Comment: 30 pages, 13 figure

    Calculation of Chirality Violating Proton Structure Function h1_1(x) in QCD

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    The twist-two chirality violating proton structure function h1(x)h_1(x) measurable in the polarized Drell-Yan process is calculated by means of QCD sum rules at intermediate xx, 0.3<x<0.70.3 < x < 0.7 and Q2510GeV2Q^2 \approx 5-10 GeV^2.Comment: 12 pages + 6 figures , LaTeX, preprint LMU-01-94. a few additions to the text; the figures have been added as uuencoded fil

    Transverse momentum dependence in gluon distribution and fragmentation functions

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    We investigate the twist two gluon distribution functions for spin 1/2 hadrons, emphasizing intrinsic transverse momentum of the gluons. These functions are relevant in leading order in the inverse hard scale in scattering processes such as inclusive leptoproduction or Drell-Yan scattering, or more general in hard processes in which at least two hadrons are involved. They show up in azimuthal asymmetries. For future estimates of such observables, we discuss specific bounds on these functions.Comment: 14 pages, revtex, 7 Postscript figure

    Accessing Transversity in Double-Spin Asymmetries at the BNL-RHIC

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    We give upper bounds for transverse double-spin asymmetries in polarized proton-proton collisions by saturating the positivity constraint for the transversity densities at a low hadronic resolution scale. We consider prompt photon, jet, pion, and heavy flavor production at the BNL Relativistic Heavy Ion Collider (RHIC). Estimates of the expected statistical accuracy for such measurements are presented, taking into account the acceptance of the RHIC detectors.Comment: 15 pages, LaTeX, 2 figures as eps file

    Habitat-dependent outdoor recreation and conservation organizations can enable recreational fishers to contribute to conservation of coastal marine ecosystems

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    Stakeholder engagement is essential to conserve ecosystems and associated biodiversity. Outdoor recreation specialists represent stakeholder groups that often rely on specific healthy ecosystems and have unique incentives to contribute to conservation and stewardship. We introduce the concept of habitat-dependent outdoor recreation conservation organizations (HDORCOs) and their potential to harness outdoor recreation enthusiasm to achieve ecosystem-scale conservation objectives. We identify potential roles for HDORCOs in nurturing pro-environmental attitudes and facilitating stewardship behavior among recreationists, focusing on examples from recreational fishing specialists and coastal marine ecosystems. While HDORCOs have achieved conservation outcomes in a range of settings, transferability across recreational specializations and ecological, cultural, socioeconomic, and governance contexts could remain challenging and potentially requires further development of the HDORCO concept. Communication with HDORCOs is one strategy to enhance engagement of recreationists, stakeholder groups not traditionally associated with pro-environmental behavior, in ecosystem-scale conservation efforts

    Q^2-Evolution of Nucleon's Chiral-Odd Twist-3 Structure Function: h_L(x,Q^2)

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    We investigate the Q2Q^{2}-evolution of the chiral-odd spin-dependent parton distribution hL(x,Q2)h_{L}(x, Q^{2}) relevant for the polarized Drell-Yan processes. The results are obtained in the leading logarithmic order in the framework of the renormalization group and the standard QCD perturbation theory. We calculate the anomalous dimension matrix for the twist-3 operators for hLh_{L} in the one-loop order. The operator mixing among the relevant twist-3 operators including the operators proportional to the QCD equations of motion is treated properly in a consistent scheme. Implications for future experiments are also discussed.Comment: HUPD-9419, Latex file, 21 pages, 7 figures available on reques

    Recent results on GaAs detectors - 137

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    The present understanding of the charge collection in GaAs detectors with respect to the materials used and its processing are discussed. The radiation induced degradation of the charge collection efficiency and the leakage current of the detectors are summarised. The status of strip and pixel detectors for the ATLAS experiment are reported along with the latest results from GaAs X-ray detectors for non-high energy physics applications.Comment: 7 pages. 4 postscript figures + 1 postscript preprint logo + 1 LaTeX file + 1 style file. Also available at http://ppewww.ph.gla.ac.uk/preprints/97/05

    The proton spin sum rule chiral bag prediction, an update

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    We reevaluate a quark model prediction using the new QCD evolution function calculated to the 3 loop order and conclude that this model compares favorably with the new experimental results.Comment: 10 pages, 2 figures available by request, give fax numbe
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