8,689 research outputs found

    Improving the J/psi Production Baseline at RHIC and the LHC

    Full text link
    We assess the theoretical uncertainties on the inclusive J/psi production cross section in the Color Evaporation Model (CEM) using values for the charm quark mass, renormalization and factorization scales obtained from a fit to the charm production data. We use our new results to provide improved baseline comparison calculations at RHIC and the LHC. We also study cold matter effects on J/psi production at leading relative to next-to-leading order in the CEM within this approach.Comment: Proceedings for Hard Probes 2012, Cagliari, Ital

    Impingement of Water Droplets on NACA 65A004 Airfoil at 8 deg Angle of Attack

    Get PDF
    The trajectories of droplets in the air flowing past an NACA 65AO04 airfoil at an angle of attack of 8 deg were determined.. The amount of water in droplet form impinging on the airfoil, the area of droplet impingement, and the rate of droplet impingement per unit area on the airfoil surface were calculated from the trajectories and presented to cover a large range of flight and atmospheric conditions. These impingement characteristics are compared briefly with those previously reported for the same airfoil at an angle of attack of 4 deg

    Space Trajectory Error Analysis Program (STEAP) for halo orbit missions. Volume 2: Programmer's manual

    Get PDF
    The six month effort was responsible for the development, test, conversion, and documentation of computer software for the mission analysis of missions to halo orbits about libration points in the earth-sun system. The software consisting of two programs called NOMNAL and ERRAN is part of the Space Trajectories Error Analysis Programs. The program NOMNAL targets a transfer trajectory from earth on a given launch date to a specified halo orbit on a required arrival date. Either impulsive or finite thrust insertion maneuvers into halo orbit are permitted by the program. The transfer trajectory is consistent with a realistic launch profile input by the user. The second program ERRAN conducts error analyses of the targeted transfer trajectory. Measurements including range, doppler, star-planet angles, and apparent planet diameter are processed in a Kalman-Schmidt filter to determine the trajectory knowledge uncertainty

    Simulated trajectories error analysis program. Volume 1 - User's manual Final report

    Get PDF
    Input/output routines and computerized simulation for error analysi

    Hamiltonian approach to QCD in Coulomb gauge - a survey of recent results

    Get PDF
    I report on recent results obtained within the Hamiltonian approach to QCD in Coulomb gauge. Furthermore this approach is compared to recent lattice data, which were obtained by an alternative gauge fixing method and which show an improved agreement with the continuum results. By relating the Gribov confinement scenario to the center vortex picture of confinement it is shown that the Coulomb string tension is tied to the spatial string tension. For the quark sector a vacuum wave functional is used which explicitly contains the coupling of the quarks to the transverse gluons and which results in variational equations which are free of ultraviolet divergences. The variational approach is extended to finite temperatures by compactifying a spatial dimension. The effective potential of the Polyakov loop is evaluated from the zero-temperature variational solution. For pure Yang--Mills theory, the deconfinement phase transition is found to be second order for SU(2) and first order for SU(3), in agreement with the lattice results. The corresponding critical temperatures are found to be 275 MeV275 \, \mathrm{MeV} and 280 MeV280 \, \mathrm{MeV}, respectively. When quarks are included, the deconfinement transition turns into a cross-over. From the dual and chiral quark condensate one finds pseudo-critical temperatures of 198 MeV198 \, \mathrm{MeV} and 170 MeV170 \, \mathrm{MeV}, respectively, for the deconfinement and chiral transition.Comment: Talk given by H. Reinhardt at "5th Winter Workshop on Non-Perturbative Quantum Field Theory", 22-24 March 2017, Sophia-Antipolis, France. arXiv admin note: text overlap with arXiv:1609.09370, arXiv:1510.03286, arXiv:1607.0814

    A two-dimensional Fermi liquid with attractive interactions

    Full text link
    We realize and study an attractively interacting two-dimensional Fermi liquid. Using momentum resolved photoemission spectroscopy, we measure the self-energy, determine the contact parameter of the short-range interaction potential, and find their dependence on the interaction strength. We successfully compare the measurements to a theoretical analysis, properly taking into account the finite temperature, harmonic trap, and the averaging over several two-dimensional gases with different peak densities

    The isotopic composition of cosmic ray B, C, N, and O nuclei

    Get PDF
    We report new high resolution measurements of the elemental and isotopic composition of galactic cosmic ray B, C, N, and O nuclei with ~ 30 to ~ 130 MeV nucleon^(-1). These observations place limits on the isotopic composition of the cosmic ray source and restrict possible models of cosmic ray origin and propagation. In particular, we find that N is significantly depleted in the cosmic ray source with respect to the solar system and local interstellar medium, a result inconsistent with models in which a majority of cosmic rays are accelerated interstellar medium material

    The isotopic composition of solar flare accelerated neon

    Get PDF
    The individual isotopes of neon in energetic solar flare particles have been clearly resolved with arms mass resolution of 0.20 amu. We find ^(20)Ne/^(22)Ne = 7.6 (+2.0, -1.8) and ^(21)Ne/^(22)Ne ≾ 0.11 in the 11-26 MeV per nucleon interval. This isotopic composition is essentially the same as that of meteoritic planetary neon-A and is significantly different from that of the solar wind

    High-Resolution Measurements of Galactic Cosmic-Ray Neon, Magnesium and Silicon Isotopes

    Get PDF
    The individual isotopes of galactic cosmic-ray Ne, Mg, and Si at ~0.20 amu. Our results suggest that the cosmic ray source is enriched in ^(22)Ne, ^(25)Mg, and ^(26)Mg when compared to the solar system. In particular, we find (^(25)Mg + ^(26)Mg)/^(24)Mg = 0.49(+0.23, -0.14) compared with the solar system value of 0.27, suggesting that the cosmic-ray source and solar system material were synthesized under different conditions

    The isotopic composition of galactic cosmic-ray iron nuclei

    Get PDF
    We report high-resolution observations made in interplanetary space of 83-284 MeV per nucleon galactic cosmic-ray iron isotopes and directly establish that ^(56)Fe is the dominant cosmic-ray Fe isotope. We find the following percentage abundances for Fe at the cosmic-ray source: ^(54)Fe = 9(+8, -5)%, ^(55)Fe ≤ 7%, ^(56)Fe = 91(+5, -11)%, ^(57)Fe ≤ 8%, and ^(58)Fe ≤ 6%. When compared to calculated nucleosynthesis yields and other observations, these results place significant constraints on the neutron excess of the environment where cosmic-ray Fe originates
    • …
    corecore