9,347 research outputs found
Approach to the Continuum Limit of the Quenched Hermitian Wilson-Dirac Operator
We investigate the approach to the continuum limit of the spectrum of the
Hermitian Wilson-Dirac operator in the supercritical mass region for pure gauge
SU(2) and SU(3) backgrounds. For this we study the spectral flow of the
Hermitian Wilson-Dirac operator in the range . We find that the
spectrum has a gap for and that the spectral density at zero,
, is non-zero for . We find that and, for
(exponential in the lattice spacing) as one goes to
the continuum limit. We also compute the topological susceptibility and the
size distribution of the zero modes. The topological susceptibility scales well
in the lattice spacing for both SU(2) and SU(3). The size distribution of the
zero modes does not appear to show a peak at a physical scale.Comment: 19 pages revtex with 9 postscript figures included by eps
Two dimensional fermions in three dimensional YM
Dirac fermions in the fundamental representation of SU(N) live on the surface
of a cylinder embedded in and interact with a three dimensional SU(N)
Yang Mills vector potential preserving a global chiral symmetry at finite .
As the circumference of the cylinder is varied from small to large, the chiral
symmetry gets spontaneously broken in the infinite limit at a typical bulk
scale. Replacing three dimensional YM by four dimensional YM introduces
non-trivial renormalization effects.Comment: 21 pages, 7 figures, 5 table
Domain Wall Fermions in Quenched Lattice QCD
We study the chiral properties and the validity of perturbation theory for
domain wall fermions in quenched lattice QCD at beta=6.0. The explicit chiral
symmetry breaking term in the axial Ward-Takahashi identity is found to be very
small already at Ns=10, where Ns is the size of the fifth dimension, and its
behavior seems consistent with an exponential decay in Ns within the limited
range of Ns we explore. From the fact that the critical quark mass, at which
the pion mass vanishes as in the case of the ordinary Wilson-type fermion,
exists at finite Ns, we point out that this may be a signal of the parity
broken phase and investigate the possible existence of such a phase in this
model at finite Ns. The rho and pi meson decay constants obtained from the
four-dimensional local currents with the one-loop renormalization factor show a
good agreement with those obtained from the conserved currents
Transport Anomalies and Marginal Fermi-Liquid Effects at a Quantum Critical Point
The behavior of the conductivity and the density of states, as well as the
phase relaxation time, of disordered itinerant electrons across a quantum
ferromagnetic transition is discussed. It is shown that critical fluctuations
lead to anomalies in the temperature and energy dependence of the conductivity
and the tunneling density of states, respectively, that are stronger than the
usual weak-localization anomalies in a disordered Fermi liquid. This can be
used as an experimental probe of the quantum critical behavior. The energy
dependence of the phase relaxation time at criticality is shown to be that of a
marginal Fermi liquid.Comment: 4 pp., LaTeX, no figs., requires World Scientific style files
(included), Contribution to MB1
Corrosion Science and Engineering
This presentation provides an overview of corrosion and corrosion prevention method
Surface pretretament by phosphate conversion coatings - A review
Phosphating is the most widely used metal pretreatment process for the surface treatment and finishing of ferrous and non-ferrous metals. Due to its economy, speed of operation and ability to afford excellent corrosion resistance, wear resistance, adhesion and lubricative
properties, it plays a significant role in the automobile, process and appliance industries. Though the process was initially developed as a simple method of preventing corrosion, the changing end uses of phosphated articles have forced the modification of the existing processes and
development of innovative methods to substitute the conventional ones. To keep pace with the rapid changing need of the finishing systems, numerous modifications have been put forth in their development - both in the processing sequence as well as in the phosphating formulations.
This review addresses the various aspects of phosphating in detail. In spite of the numerous modifications put forth on the deposition technologies to achieve different types of coatings and desirable properties such as improved corrosion resistance, wear resistance, etc., phosphate conversion coating still plays a vital part in the automobile, process and appliance industries
The role of surfactants in phosphate conversion coatings
Surface active agents occupy a predominant role in the metal finishing industry. Being capable of reducing the surface tension and improving the wettability of the surface, the importance of such additives is very well realized and phosphating baths have been developed with surfactants as one of the additives. However, surfactant additives could influence the nucleation and growth of phosphate crystals and alter the kinetics of the phosphating process. Addition of surfactants in phosphating baths is beneficial in obtaining the desired orientation of the phosphate crystal and the crystallites of the base metal, leading to an improved adherence and excellent corrosion resistance of the resultant phosphate coating. The influence of surfactant additives on the nucleation, growth, refinement of crystals and the continuous dissolution and re-precipitation of the phosphate coating, calls for a through understanding of role of surfactant additives often incorporated in phosphating baths so that the desirable qualities can be successfully built-in in the resultant phosphate coating
Graphene - Its role in energy storage devices
This presentation provides an overview of graphene, methods of preparation of graphene, important applications and its role in energy storage devices, namely, fuel cells, supercapacitors, lithium batteries and hydrogen storage
Magnesium: A wonder material?
This presentation is aimed to give a glimpse of the role of Mg in human life and healt
Tin plated contacts - Problems due to fretting corrosion and whisker growth
This presentation provides an overview of the most common type of failures in tin plated contacts - fretting corrosion and whisker growth. The fretting corrosion behaviour of tin plated copper contacts as a function of different conditions were addressed. The mechamism of fretting corrosion is proposed
- …