7,483 research outputs found

    Open Questions in the Understanding of Strangeness Production in HIC -- Experiment Perspective

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    Open questions concerning strangeness production in heavy-ion collisions are discussed with a focus on the experimental aspects. The open points are presented in the context of recent measurements.Comment: Proceedings for the Strange Quark Matter 2017 conference in Utrecht, Netherland

    Strangeness Production at the SPS

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    Systematic studies on the production of strange hyperons and the phi meson as a function of beam energy and system size performed by the NA49 collaboration are discussed. Hadronic transport models fail to describe the production of multi strange particles (Xi, Omega), while statistical models are generally in good agreement to the measured particle yields at all energies. The system size dependence is well reproduced by the core-corona approach. New data on K*(892) production are presented. The yields of these short-lived resonances are significantly below the statistical model expectation. This is in line with the interpretation that the measurable yields are reduced due to rescattering of their decay products inside the fireball.Comment: Proceedings to the ISMD09 Conference. 5 pages, 6 figure

    Stopping in central Pb + Pb collisions at SPS energies and beyond

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    We investigate stopping and baryon transport in central relativistic Pb + Pb and Au + Au collisions. At energies reached at the CERN Super Proton Synchrotron [sqrt(s_NN) = 6.3-17.3 GeV] and at RHIC (62.4 GeV), we determine the fragmentation-peak positions from the data. The resulting linear growth of the peak positions with beam rapidity is in agreement with our results from a QCD-based approach that accounts for gluon saturation. No discontinuities in the net-proton fragmentation peak positions occur in the expected transition region from partons to hadrons at 6-10 GeV.Comment: 5 pages, 3 figures, 1 table. Figures updated, table shortened, 1 reference adde

    Application of pressurized liquid nitrogen inside parametric-amplifier structures for input-noise-temperature improvement

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    Pressurized liquid nitrogen inside parametric amplifier structures for input, noise, and temperature improvement

    Unification and limitations of error suppression techniques for adiabatic quantum computing

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    While adiabatic quantum computation (AQC) possesses some intrinsic robustness to noise, it is expected that a form of error control will be necessary for large scale computations. Error control ideas developed for circuit-model quantum computation do not transfer easily to the AQC model and to date there have been two main proposals to suppress errors during an AQC implementation: energy gap protection and dynamical decoupling. Here we show that these two methods are fundamentally related and may be analyzed within the same formalism. We analyze the effectiveness of such error suppression techniques and identify critical constraints on the performance of error suppression in AQC, suggesting that error suppression by itself is insufficient for fault-tolerant, large-scale AQC and that a form of error correction is needed. This manuscript has been superseded by the articles, "Error suppression and error correction in adiabatic quantum computation I: techniques and challenges," arXiv:1307.5893, and "Error suppression and error correction in adiabatic quantum computation II: non-equilibrium dynamics," arXiv:1307.5892.Comment: 9 pages. Update replaces "Equivalence" with "Unification." This manuscript has been superseded by the two-article series: arXiv:1307.5892 and arXiv:1307.589

    System Size Dependence of Particle Production at the SPS

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    Recent results on the system size dependence of net-baryon and hyperon production as measured at the CERN SPS are discussed. The observed Npart dependences of yields, but also of dynamical properties, such as average transverse momenta, can be described in the context of the core corona approach. Other observables, such as antiproton yields and net-protons at forward rapidities, do not follow the predictions of this model. Possible implications for a search for a critical point in the QCD phase diagram are discussed. Event-by-event fluctuations of the relative core to corona source contributions might influence fluctuation observables (e.g. multiplicity fluctuations). The magnitude of this effect is investigated.Comment: 10 pages, 4 figurs. Proceedings of the 6th International Workshop on Critical Point and Onset of Deconfinement in Dubna, Aug. 201

    The Trapped Polarized Fermi Gas at Unitarity

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    We consider population-imbalanced two-component Fermi gases under external harmonic confinement interacting through short-range two-body potentials with diverging s-wave scattering length. Using the fixed-node diffusion Monte Carlo method, the energies of the "normal state" are determined as functions of the population-imbalance and the number of particles. The energies of the trapped system follow, to a good approximation, a universal curve even for fairly small systems. A simple parameterization of the universal curve is presented and related to the equation of state of the bulk system.Comment: 4 pages, 2 tables, 2 figure
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