15,284 research outputs found
Degradation of multiplier phototubes exposed to spatial radiations
Degradation of multiplier phototubes exposed to spatial radiation
Four-point functions and kaon decays in a minimal AdS/QCD model
We study the predictions of holographic QCD for various observable four-point
quark flavour current-current correlators. The dual 5-dimensional bulk theory
we consider is a Yang Mills theory in a slice of
spacetime with boundaries. Particular UV and IR boundary conditions
encode the spontaneous breaking of the dual 4D global chiral symmetry down to
the subgroup. We explain in detail how to calculate the 4D four-point
quark flavour current-current correlators using the 5D holographic theory,
including interactions. We use these results to investigate predictions of
holographic QCD for the rule for kaon decays and the
parameter. The results agree well in comparison with experimental data, with an
accuracy of 25% or better. The holographic theory automatically includes the
contributions of the meson resonances to the four-point correlators. The
correlators agree well in the low-momentum and high-momentum limit, in
comparison with chiral perturbation theory and perturbative QCD results,
respectively.Comment: Published version, title changed to conform with Journal format,
references and clarifying remarks added, 40 pages, 5 figure
Subthreshold characteristics of pentacene field-effect transistors influenced by grain boundaries.
Grain boundaries in polycrystalline pentacene films significantly affect the electrical characteristics of pentacene field-effect transistors (FETs). Upon reversal of the gate voltage sweep direction, pentacene FETs exhibited hysteretic behaviours in the subthreshold region, which was more pronounced for the FET having smaller pentacene grains. No shift in the flat-band voltage of the metal-insulator-semiconductor capacitor elucidates that the observed hysteresis was mainly caused by the influence of localized trap states existing at pentacene grain boundaries. From the results of continuous on/off switching operation of the pentacene FETs, hole depletion during the off period is found to be limited by pentacene grain boundaries. It is suggested that the polycrystalline nature of a pentacene film plays an important role on the dynamic characteristics of pentacene FETs
High Energy Physics from High Performance Computing
We discuss Quantum Chromodynamics calculations using the lattice regulator.
The theory of the strong force is a cornerstone of the Standard Model of
particle physics. We present USQCD collaboration results obtained on Argonne
National Lab's Intrepid supercomputer that deepen our understanding of these
fundamental theories of Nature and provide critical support to frontier
particle physics experiments and phenomenology.Comment: Proceedings of invited plenary talk given at SciDAC 2009, San Diego,
June 14-18, 2009, on behalf of the USQCD collaboratio
Mean field baryon magnetic moments and sumrules
New developments have spurred interest in magnetic moments (-s) of
baryons. The measurement of some of the decuplet -s and the findings of
new sumrules from various methods are partly responsible for this renewed
interest. Our model, inspired by large colour approximation, is a relativistic
self consistent mean field description with a modified Richardson potential and
is used to describe the -s and masses of all baryons with up (u), down (d)
and strange (s) quarks. We have also checked the validity of the Franklin
sumrule (referred to as CGSR in the literature) and sumrules of Luty,
March-Russell and White. We found that our result for sumrules matches better
with experiment than the non-relativistic quark model prediction. We have also
seen that quark magnetic moments depend on the baryon in which they belong
while the naive quark model expects them to be constant.Comment: 7 pages, no figure, uses epl.cl
Refrigerant forced-convection condensation inside horizontal tubes
High vapor velocity condensation inside a tube was studied theoretically. The heat transfer coefficients were calculated by the momentum and heat transfer analogy. The Von Karman universal velocity distribution was applied to the condensate flow. Pressure drop was calculated by the Lockhart-Martinelli method and the Zivi void fraction equation. Experimental data was obtained for the flow rate from 240,000 to 485,000 lbm/ft2 hr. R-22 was condensed in a 0.493" I.D. 18 ft. long test section. The measured heat transfer coefficients agreed with the prediction within 10% except a few points in the very low quality region.Sponsored by American Society of Heating, Refrigerating and Air Conditioning Engineers DS
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