1,042 research outputs found
Chiral Symmetry Breaking for Domain Wall Fermions in Quenched Lattice QCD
The domain wall fermion formulation exhibits full chiral symmetry for finite
lattice spacing except for the effects of mixing between the domain walls.
Close to the continuum limit these symmetry breaking effects should be
described by a single residual mass. We determine this mass from the
conservation law obeyed by the conserved axial current in quenched simulations
with beta=5.7 and 6.0 and domain wall separations varying between 12 and 48 on
8^3x32 and 16^3x32 lattices. Using the resulting values for the residual mass
we perform two complete and independent calculations of the pion decay
constant. Good agreement is found between these two methods and with
experiment.Comment: 4 pages, 6 figures, Lattice 2000 (Chiral Fermions), RBC Collaboratio
QCD hadron spectrum with domain wall fermions
We present the QCD hadron spectrum for the cases of both quenched and
two-flavor dynamical domain wall fermions. We compare the results obtained
using the Wilson gauge action and a renormalization group improved gauge
action. Finite volume effects and the dependence on the finite extent of the
fifth dimension are discussed.Comment: LATTICE99(QCD spectrum), 3 pages, 2 figures. Work done with CU and
RIKEN/BNL/CU collaboratio
Surface processing by RFI PECVD and RFI PSII
An RFI plasma enhanced chemical vapor deposition (PECVD) system and a large-scale RF plasma source immersion ion implantation (PSII) system were designed and built to study two forms of 3-D surface processing, PECVD and PSII. Using the RFI PECVD system, Ti-6Al-4V substrates were coated with diamond-like carbon films with excellent tribological and optical properties. as an innovation, variable angle spectroscopic ellipsometry (VASE) was successfully applied for non-destructive, 3-D, large-area tribological coatings quality investigation.;Based on the experience with the RFI PECVD system, a large-scale RFICP source was designed and built for the PSIL Langmuir probe and optical emission spectroscopy studies indicated that the RFI source produced stable, uniform, and clean plasma. MAGIC code was for the first time used to model PSII process, addressing different target geometries and boundaries, materials, plasma parameters, illustrated sheath formation and evolution, field distribution, ion and electron trajectories, ion incident angles, and dose distributions, which are critical for PSII design and understanding.;The RF PSII system was developed into a versatile large-area, uniform, 3-D surface processing apparatus, capable of PSII, PVD, PECVD, and in situ surface cleaning and interface properties modification, for multilayer, multi-step, and high performance surface engineering. Using the RFI PSII system, for the first time, PSII was studied as a mask-based surface layer conversion technique, for pattern writing by implantation as an alternative to current deposition-based and ink-based direct write technologies. It operates at low substrate temperature, keeps the original surface finish and dimensions, and avoids adhesion problem. A different operating mode of the RF source was discovered to perform biased sputtering of high purity quartz, which turned the RFI PSII system into a novel integrated RF PSII/PVD system for large-area, uniform, nitrogen-doped, and hydrogen-free SiO2 films deposition at low substrate temperatures. Nitrogen-doped SiO2 films with excellent optical properties were deposited on semiconductor, metal, and polymer substrates with excellent adhesion. Ellipsometry was used again for non-destructive SiO2 coatings investigation. FEL test electrodes processed by PSII/PVD showed suppressed field emission. A group of transition metals and an FEL test electrode were also implanted by nitrogen using the PSII mode and analyzed
Bogdanov-Takens bifurcation of codimension in the Gierer-Meinhardt model
Bifurcation of the local Gierer-Meinhardt model is analyzed in this paper. It
is found that the degenerate Bogdanov-Takens bifurcation of codimension 3
happens in the model, except that teh saddle-node bifurcation and the Hopf
bifurcation. That was not reported in the existing results about this model.
The existence of equilibria, their stability, the bifurcation and the induced
complicated and interesting dynamics are explored in detail, by using the
stability analysis, the normal form method and bifurcation theory. Numerical
results are also presented to validate theoretical results
A Study on the Cultivation of Primary School Students’ Cross-cultural Awareness—Based on the Schema Theory
The cultivation of cross-cultural awareness for primary students is a key point in the English class. Apart from the traditional method, schema theory will be a new way for it. This paper investigates the current situation of primary school and analyses the problems in class. It explores the effective methods under the schema theory and provides relevant suggestions
- …