66,622 research outputs found

    Tomographic Studies of the sQGP

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    Azimuthal correlation functions are used to study jet- and di-jet properties as a function of centrality in Au+Au collisions at sNN\sqrt{s_{_{\rm NN}}}=200 GeV. Utilizing a novel technique to decompose the correlation function into a (di-)jet and an underlying event, the jet-pair distribution is extracted and compared to similar results for d+Au collisions obtained at the same collision energy. A striking similarity is observed between the widths and associated yields of the (di-)jet distributions for d+Au and peripheral Au+Au collisions. By contrast, the distributions for mid-central Au+Au collisions indicate an increase in the di-jet yield with centrality, and a very broad away-side jet having a possible minimum at Δϕπ\Delta\phi \approx \pi. These features point to significant medium induced modification to the away-side jet and are compatible with recent predictions of jet-induced "conical flow".Comment: Proc. 21st. Winter Workshop on Nuclear Dynamic

    A duality for the double fibration transform

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    We establish a duality within the spectral sequence that governs the holomorphic double fibration transform. It has immediate application to the questions of injectivity and range characterization for this transform. We discuss some key examples and an improved duality that holds in the Hermitian holomorphic case

    MHOs toward HMOs: A Search for Molecular Hydrogen emission-line Objects toward High-Mass Outflows

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    We present the results of a narrow-band near-infrared imaging survey for Molecular Hydrogen emission-line Objects (MHOs) toward 26 regions containing high-mass protostellar candidates and massive molecular outflows. We have detected a total of 236 MHOs, 156 of which are new detections, in 22 out of the 26 regions. We use H2_2 2.12-μ\mum/H2_2 2.25-μ\mum flux ratios, together with morphology, to separate the signatures of fluorescence associated with photo-dissociation regions (PDRs) from shocks associated with outflows in order to identify the MHOs. PDRs have typical low flux ratios of ~ 1.5 - 3, while the vast majority of MHOs display flux ratios typical of C-type shocks (~ 6-20). A few MHOs exhibit flux ratios consistent with expected values for J-type shocks (~ 3-4), but these are located in regions that may be contaminated with fluorescent emission. Some previously reported MHOs have low flux ratios, and are likely parts of PDRs rather than shocks indicative of outflows. We identify a total of 36 outflows across the 22 target regions where MHOs were detected. In over half these regions, MHO arrangements and fluorescent structures trace features present in CO outflow maps, suggesting the CO emission traces a combination of dynamical effects, which may include gas entrained in expanding PDRs as well as bipolar outflows. Where possible, we link MHO complexes to distinct outflows and identify candidate driving sources.Comment: 40 pages, 40 figures, accepted for publication in the Astrophysical Journa

    Analysis of Dilepton Invariant Mass Spectrum in C+C at 2 and 1 AGeV

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    Recently the HADES collaboration has published the invariant mass spectrum of e+ee^+e^- pairs, dN/dMe+e_{e^+e^-}, produced in C+C collisions at 2 AGeV. Using electromagnetic probes, one hopes to get in this experiment information on hadron properties at high density and temperature. Simulations show that firm conclusions on possible in-medium modifications of meson properties will only be possible when the elementary meson production cross sections, especially in the pn channel, as well as production cross sections of baryonic resonances are better known. Presently one can conclude that a) simulations overpredict by far the cross section at Me+eMω0M_{e^+e^-} \approx M_{\omega}{^0} if free production cross sections are used and that b) the upper limit of the η\eta decay into e+ee^+e^- is smaller than the present upper limit of the Particle Data Group. This is the result of simulations using the Isospin Quantum Molecular Dynamics (IQMD) approach.Comment: 28 pages, 15 figures, 3 tables, ps file recommende

    Measuring the Decorrelation Times of Fourier Modes in Simulations

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    We describe a method to study the rate at which modes decorrelate in numerical simulations. We study the XY model updated with the Metropolis and Wolff dynamics respectively and compute the rate at which each eigenvector of the dynamics decorrelates. Our method allows us to identify the decorrelation time for each mode separately. We find that the autocorrelation function of the various modes is markedly different for the `local' Metropolis compared to the `non-local' Wolff dynamics. Equipped with this new insight, it may be possible to devise highly efficient algorithms.Comment: 16 pp (LaTeX), PUPT-1378 , IASSNS-HEP-93/

    Comparing Hemp Seed Yields (Cannabis sativa L.) of an On-Farm Scientific Field Experiment to an On-Farm Agronomic Evaluation Under Organic Growing Conditions in Lower Austria

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    Hemp seed yields of the variety Fedora-19 in an on-farm scientific field experiment on small plots and in an on-farm evaluation in 11 hemp fields under practical organic growing conditions in Lower Austria were compared to give a realistic view of the variability of yields. Dry matter seed yields from the on-farm field experiment ranged from 127 to 143 g/m2. Under practical growing conditions, yields ranged from 34 to 151 g/m2 in the sample plots. The reported hemp seed yield after combine harvesting, drying, and cleaning was between 324 kg/ha and 717 kg/ha. The results of the experiment show that harvesting by hand considerably influences yields. Yields of the manual harvest in sample plots indicate a high correlation with yields harvested by the combine harvester (R2 = 0.91). The commercial yield is 71% of the yields recorded in sample plots in the fields. Our data questions the transfer of results and conclusions drawn from the data of scientific field experiments that employ manual harvest to that of practical circumstances, and support the notion of on-farm research

    Zero temperature properties of mesons in a vector meson extended linear sigma model

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    A three flavor linear sigma model with vector and axial-vector mesons is discussed. Preliminary results concerning on the symmetry breaking pattern, the question of parameterization, as well as the resulting meson masses are presented.Comment: 4 pages, 0 figures, submitted to the Hot and Cold Baryonic Matter (HCBM 2010) conference proceeding
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