12,698 research outputs found
Constructing Confinement
The interaction between static quarks is derived by applying many-body
techniques to QCD in Coulomb gauge. The result is shown to be exact in the IR
and UV limits, and agrees remarkably well with lattice computations.Comment: 6 pages, 3 figures, proceedings for 2002 Lake Louise Winter Institut
Improved particle charging technique final report
High current ion beam for improving particle charging - hypervelocity accelerato
Radiation counting technique allows density measurement of metals in high-pressure/ high-temperature environment
Radioactive tracers induced by neutron irradiation provide a gamma ray flux proportional to the density of a metal, allowing density measurement of these metals in extreme high-temperature and high-pressure environments. This concept is applicable to most metals, as well as other substances
A Coulomb Gauge Model of Mesons
A model of mesons which is based on the QCD Hamiltonian in Coulomb gauge is
presented. The model relies on a novel quasiparticle basis to improve the
reliability of the Fock space expansion. It is also relativistic, yields chiral
pions, and is tightly constrained by QCD (quark masses are the only
parameters). Applications to hidden flavor mesons yield results which are
comparable to phenomenological constituent quark models while revealing the
limitations of such models.Comment: 13 pages, 1 eps figure, 5 table
Coupling hydrophobic, dispersion, and electrostatic contributions in continuum solvent models
Recent studies of the hydration of micro- and nanoscale solutes have
demonstrated a strong {\it coupling} between hydrophobic, dispersion and
electrostatic contributions, a fact not accounted for in current implicit
solvent models. We present a theoretical formalism which accounts for coupling
by minimizing the Gibbs free energy with respect to a solvent volume exclusion
function. The solvent accessible surface is output of our theory. Our method is
illustrated with the hydration of alkane-assembled solutes on different length
scales, and captures the strong sensitivity to the particular form of the
solute-solvent interactions in agreement with recent computer simulations.Comment: 11 pages, 2 figure
Life prediction and constitutive models for engine hot section anisotropic materials program
This report presents the results of the first year of a program designed to develop life prediction and constitutive models for two coated single crystal alloys used in gas turbine airfoils. The two alloys are PWA 1480 and Alloy 185. The two oxidation resistant coatings are PWA 273, an aluminide coating, and PWA 286, an overlay NiCoCrAlY coating. To obtain constitutive and/or fatigue data, tests were conducted on coated and uncoated PWA 1480 specimens tensilely loaded in the 100 , 110 , 111 , and 123 directions. A literature survey of constitutive models was completed for both single crystal alloys and metallic coating materials; candidate models were selected. One constitutive model under consideration for single crystal alloys applies Walker's micromechanical viscoplastic formulation to all slip systems participating in the single crystal deformation. The constitutive models for the overlay coating correlate the viscoplastic data well. For the aluminide coating, a unique test method is under development. LCF and TMF tests are underway. The two coatings caused a significant drop in fatigue life, and each produced a much different failure mechanism
Electron Bernstein waves in spherical tokamak plasmas with "magnetic wells"
In addition to traditional regimes with monotonously increasing magnetic
field, regimes with "magnetic wells" also occur in spherical tokamaks (STs).
The magnetic field profile inversion modifies significantly the whole picture
of the wave propagation and damping. Since the magnetic wells may become quite
common with further improvement of ST performance, analysis of such
configurations is of interest for assessment of EBW plasma heating an CD
perspectives. In this paper the basic features of the EBWs propagation and
damping for the second cyclotron harmonic in a slab model are considered.Comment: Proc. of 13-th Joint Workshop on ECE and ECRH, N.Novgorod, Russia May
17-20, 2004, 8 pages, 4 fig
Inflation Assisted by Heterotic Axions
We explore the possibility of obtaining inflation in weakly coupled heterotic
string theory, where the model dependent axions are responsible for driving
inflation. This model can be considered as a certain extrapolation of
-inflation, and is an attempt to explicitly realize the so
called N-flation proposal in string theory. The instanton generated potential
for the axions essentially has two parameters; a natural mass scale and the
string coupling . For isotropic compactifications leading to of order
axions in the four dimensional spectrum we find that with
the observed temperature fluctuations in the
CMB are correctly reproduced. We assume an initially random distribution for
the vevs of the axions. The spectral index, , is generically more red
than for -inflation. The greater the vevs, the more red the
spectral index becomes. Allowing for a wide range of vevs 55 -foldings from
the end of inflation, we find . The
tensor-to-scalar ratio, , is more sensitive to the vevs, but typically
smaller than in -inflation. Furthermore, in the regime where the
leading order theory is valid, is bounded by . The spectral index
and the tensor-to-scalar ratio are correlated. For example,
corresponds to .Comment: 1+21 pages, 2 figures, v2: Typos corrected, v3: Typos, very minor
corrections, reference added, to appear in JCA
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