2,392 research outputs found

    Charmonium production from nonequilibrium charm and anticharm quarks in quark-gluon plasma

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    Parameterizing the charm and anticharm quark momentum distributions by the Tsallis distribution, we study the nonequilibrium effect on the charmonium production rate in a quark-gluon plasma up to the next-to-leading order in perturbative QCD. We find that nonequilibrium charm and anticharm quarks suppress the charmonium production rate compared to that from equilibrated ones. We further show that the suppression factor calculated with the charm quark relaxation time, which has been frequently used in the literature, is close to our results.Comment: 8 pages, 5 figure

    Jet Fragmentation via Recombination of Parton Showers

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    We study hadron production in jets by applying quark recombination to jet shower partons. With the jet showers obtained from PYTHIA and augmented by additional non-perturbative effects, we compute hadron spectra in e+ + e-collisions at sqrt(s)=200 GeV. Including contributions from resonance decays, we find that the resulting transverse momentum spectra for pions, kaons, and protons reproduce reasonably those from the string fragmentation as implemented in PYTHIA.Comment: 4 pages, 3 figures, contribution to Nucleus-Nucleus Collisions 201

    An Examination On Factors That Influence The Creation Of Economic Value Added To The Professional Teams: Focusing On Korea Baseball Organization (KBO)

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    The research seeks to derive the economic value added (EVA) of 6 franchises from the Korea Baseball Organization (KBO) and concurrently investigate the revenue components contributing to EVA. EVA is regarded as one of the efficient methods on estimating or assessing corporations’ actual economic benefits. For the procedure, financial statements of domestic professional baseball teams for 3 consecutive years (2016-2018), which were released to the Data Analysis Retrieval and Transfer System (DART) of the Financial Supervisory Service (FSS), were utilized. First, NOPLAT, IC, ROIC, and WACC, which refer to essential elements of estimating the EVA, were calculated respectively. Second, Pearson's correlation analysis was conducted between the EVA and the profit indicated in the income statement of the 6 teams. The results of the study are as follows: In case of Doosan, LG and SK, main business revenues showed the highest correlation with EVA, and Kiwoom and Samsung showed the highest correlation with EVA through the contributing factor of ticket sales revenue. Finally, for Lotte, advertising revenue was highly correlated with bringing EVA to the tea

    Charmonium production in heavy-ion collisions from SPS to LHC

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    Using the two-component model that includes charmonium production from initial nucleon-nucleon hard scattering and regeneration in the produced quark-gluon plasma, we study J/ψJ/\psi production in heavy ion collisions at SPS, RHIC and LHC. For the expansion dynamics of produced hot dense matter, we use a schematic viscous hydrodynamic model with the specific shear viscosity taken, respectively, to be twice and ten times the lower bound of 1/4π1/4\pi suggested by the Ads/CFT correspondence in the quark-gluon plasma and in the hadron gas. For the initial dissociation and the subsequent thermal decay of charmonia in the hot dense matter, we use the screened Cornell potential to describe the properties of charmonia and the perturbative QCD to calculate their dissociation cross sections. Including regeneration of charmonia in the quark-gluon plasma via a kinetic equation with in-medium chamonium decay widths, we obtain a good description of measured nuclear modification factors at SPS and RHIC. A reasonable description of measured nuclear modification factor of J/ψJ/\psis of high transverse momenta in heavy ion collisions at LHC is also obtained if we include the contribution to the J/ψJ/\psi yield from the decay of bottomed hadrons.Comment: 10 pages, 11 figure

    Dilepton production in schematic causal viscous hydrodynamics

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    Journals published by the American Physical Society can be found at http://publish.aps.org/Assuming that in the hot dense matter produced in relativistic heavy-ion collisions, the energy density, entropy density, and pressure as well as the azimuthal and space-time rapidity components of the shear tensor are uniform in the direction transversal to the reaction plane, we derive a set of schematic equations from the Isreal-Stewart causal viscous hydrodynamics. These equations are then used to describe the evolution dynamics of relativistic heavy-ion collisions by taking the shear viscosity to entropy density ratio of 1/4 pi for the initial quark-gluon plasma (QGP) phase and of 10 times this value for the later hadron-gas (HG) phase. Using the production rate evaluated with particle distributions that take into account the viscous effect, we study dilepton production in central heavy-ion collisions. Compared with results from the ideal hydrodynamics, we find that although the dilepton invariant mass spectra from the two approaches are similar, the transverse momentum spectra are significantly enhanced at high transverse momenta by the viscous effect. We also study the transverse momentum dependence of dileptons produced from QGP for a fixed transverse mass, which is essentially absent in the ideal hydrodynamics, and find that this so-called transverse mass scaling is violated in the viscous hydrodynamics, particularly at high transverse momenta

    Determination of Cutting Date and Interval on Native Grass Management of Agricultural Waterways in South Korea

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    Agricultural waterways provide a buffer zone between crop fields and adjacent rivers or streams. Waterways are important resource for agriculture water management, water quality and biodiversity conservation. The total linear distance of waterway in Korea is about 180,000 km, and about 40% are concrete and about 60% are grassed waterways. At present, the percentage of concrete waterways is increasing because of their water management efficiency. Some argue that continued expansion of concrete waterways is not sustainable because it leads to potential-degradation of the earth\u27s environment. This concern has led to renewed efforts to use grassed waterways as an alternative to concrete. In addition, grassed waterways enhance the environment-friendly image of agriculture that Korea farmers want to promote. The objective of this experiment was to determine the effect of cutting date and interval of native grasses for water management efficiency of agricultural waterway

    Extreme Drug Resistance in Acinetobacter baumannii Infections in Intensive Care Units, South Korea

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    BACKGROUND: Difference in adaptability responses to stress has been observed amongst bird species, strains, and individuals. Components of the HPA axis, one of the internal systems involved in homeostasis re-establishment following stress, could play a role in this variability of responses. The aim of the present study was 1) to identify genes involved in the regulation of adrenal activity following ACTH stimulation and 2) to examine adrenal genes differentially expressed in individuals with high and low plasma corticosterone response following ACTH treatment. RESULTS: Analysis with 21 K poultry oligo microarrays indicated that ACTH treatment affected the expression of 134 genes. Several transcripts assigned to genes involved in the adrenal ACTH signaling pathway and steroidogenic enzymes were identified as differentially expressed by ACTH treatment. Real-time PCR on 18 selected genes confirmed changes in transcript levels of 11 genes, including MC2R, CREM, Cry, Bmal1, Sqle, Prax1, and StAR. Only 4 genes revealed to be differentially expressed between higher and lower adrenal responders to ACTH treatment. CONCLUSION: The results from the present study reveal putative candidate genes; their role in regulation of adrenal functions and adaptability to stress should be further investigated
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