36,663 research outputs found
Higher and missing resonances in omega photoproduction
We study the role of the nucleon resonances () in
photoproduction by using the quark model resonance parameters predicted by
Capstick and Roberts. The employed and
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 , a missing resonance, and which is
identified as the 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
It is shown that the relative sign between the and
coupling constants can be determined most sensitively from production
processes in collisions. Recent data on these reactions clearly favor the
sign of the 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
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
The heavy quark system is an excellent probe to learn about the QCD dynamics
at finite density. First, we discuss the properties of the and
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
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
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
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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