36,664 research outputs found

    Higher and missing resonances in omega photoproduction

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    We study the role of the nucleon resonances (NN^*) in ω\omega photoproduction by using the quark model resonance parameters predicted by Capstick and Roberts. The employed γNN\gamma N \to N^* and NωNN^* \to \omega N amplitudes include the configuration mixing effects due to the residual quark-quark interactions. The contributions from the nucleon resonances are found to be important in the differential cross sections at large scattering angles and various spin observables. In particular, the parity asymmetry and beam-target double asymmetry at forward scattering angles are suggested for a crucial test of our predictions. The dominant contributions are found to be from N32+(1910)N\frac32^+ (1910), a missing resonance, and N32(1960)N\frac32^- (1960) which is identified as the D13(2080)D_{13}(2080) of the Particle Data Group.Comment: 8 pages, LaTeX with ws-p8-50x6-00.cls, 4 figures (5 eps files), Talk presented at the NSTAR2001 Workshop on the Physics of Excited Nucleons, Mainz, Germany, Mar. 7-10, 200

    On the sign of the pi-rho-omega coupling constant

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    It is shown that the relative sign between the NNωNN\omega and πρω\pi\rho\omega coupling constants can be determined most sensitively from ω\omega production processes in NNNN collisions. Recent data on these reactions clearly favor the sign of the πρω\pi\rho\omega coupling constant which is opposite to that inferred from studies of the photoproduction reaction in combination with the vector meson dominance assumption and used by many authors. Implication of this finding in the description of other reactions is discussed.Comment: 6 pages, 4 figures, REVTeX, to be published in Phys. Lett.

    Determination of the gaseous hydrogen ductile-brittle transition in copper-nickel alloys

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    A series of copper-nickel alloys were fabricated, notched tensile specimens machined for each alloy, and the specimens tested in 34.5 MPa hydrogen and in air. A notched tensile ratio was determined for each alloy and the hydrogen environment embrittlement (HEE) determined for the alloys of 47.7 weight percent nickel to 73.5 weight percent nickel. Stacking fault probability and stacking fault energies were determined for each alloy using the x ray diffraction line shift and line profiles technique. Hydrogen environment embrittlement was determined to be influenced by stacking fault energies; however, the correlation is believed to be indirect and only partially responsible for the HEE behavior of these alloys

    Charmonium-hadron interactions from QCD

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    The heavy quark system is an excellent probe to learn about the QCD dynamics at finite density. First, we discuss the properties of the J/ψJ/\psi and DD meson at finite nucleon density. We discuss why their properties should change at finite density and then introduce an exact QCD relation among these hadron properties and the energy momentum tensor of the medium. Second, we discuss attempts to calculate charmonium-hadron total cross section using effective hadronic models and perturbative QCD. We emphasize a recent calculation, where the cross section is derived using QCD factorization theorem. We conclude by discussing some challenges for SIS 200.Comment: 8 pages, Presented at 6th International Conference on Strange Quarks in Matter: 2001: A Flavorspace Odyssey (SQM2001), Frankfurt, Germany, 25-29 Sep 2001, submitted to J. Phys.

    Energy levels of the soliton--heavy-meson bound states

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    We investigate the bound states of heavy mesons with finite masses to a classical soliton solution in the Skyrme model. For a given model Lagrangian we solve the equations of motion exactly so that the heavy vector mesons are treated on the same footing as the heavy pseudoscalar mesons. All the energy levels of higher grand spin states as well as the ground state are given over a wide range of the heavy meson masses. We also examine the validity of the approximations used in the literatures. The recoil effect of finite mass soliton is naively estimated.Comment: 24 pages, REVTeX v3.0, 6 figures are available upon request

    Hierarchy of measurement-induced Fisher information for composite states

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    Quantum Fisher information, as an intrinsic quantity for quantum states, is a central concept in quantum detection and estimation. When quantum measurements are performed on quantum states, classical probability distributions arise, which in turn lead to classical Fisher information. In this article, we exploit the classical Fisher information induced by quantum measurements, and reveal a rich hierarchical structure of such measurement-induced Fisher information. We establish a general framework for the distribution and transfer of the Fisher information. In particular, we illustrate three extremal distribution types of the Fisher information: the locally owned type, the locally inaccessible type, and the fully shared type. Furthermore, we indicate the significant role played by the distribution and flow of the Fisher information in some physical problems, e.g., the non-Markovianity of open quantum processes, the environment-assisted metrology, the cloning and broadcasting, etc.Comment: 6 page

    An exploration of think-aloud protocols linked with eye-gaze tracking: Are they talking about what they are looking at

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    This pilot study investigated the use of juxtaposed think aloud and eye-gaze tracking to understand a possible different understanding of think aloud process of participants. Four participants completed eight multiple-choice science questions while thinking aloud and having their eye-gazes tracked. Analysis of the data revealed that participants had behaviors such as fore telling of an eye movement, pauses in the think-aloud, different duration of the think-aloud, and the interaction between the think-aloud and associated eye movements. These findings suggest that juxtaposed think aloud and eye-gaze tracking may be a useful approach to furthering our understanding of students’ problem solving behaviors
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