Towards a lattice calculation of the coefficients of the QCD chiral Lagrangian

We discuss a general strategy to compute the coefficients of QCD chiral Lagrangian by using the lattice regularization of QCD with Wilson fermions. This procedure requires the introduction of an effective Lagrangian for lattice QCD as an intermediate step in the calculation. The continuum QCD chiral Lagrangian can be then obtained by expanding the lattice effective Lagrangian in increasing powers of the external momenta. A suitable renormalization procedure is required to account for the chiral symmetry breaking introduced by the Wilson term in the lattice action. In anticipation of a numerical simulation, the lattice effective Lagrangian is computed analytically and investigated in the strong coupling and large $N$ limitComment: Talk presented at LATTICE96(chirality in qcd) , 3 pages, no figures. Latex file with espcrc2 styl

Quantum Isometrodynamics

Classical Isometrodynamics is quantized in the Euclidean plus axial gauge. The quantization is then generalized to a broad class of gauges and the generating functional for the Green functions of Quantum Isometrodynamics (QID) is derived. Feynman rules in covariant Euclidean gauges are determined and QID is shown to be renormalizable by power counting. Asymptotic states are discussed and new quantum numbers related to the "inner" degrees of freedom introduced. The one-loop effective action in a Euclidean background gauge is formally calculated and shown to be finite and gauge-invariant after renormalization and a consistent definition of the arising "inner" space momentum integrals. Pure QID is shown to be asymptotically free for all dimensions of "inner" space $D$ whereas QID coupled to the Standard Model fields is not asymptotically free for D <= 7. Finally nilpotent BRST transformations for Isometrodynamics are derived along with the BRST symmetry of the theory and a scetch of the general proof of renormalizability for QID is given.Comment: 38 page

Oscillating bounce solutions and vacuum tunneling in de Sitter spacetime

We study a class of oscillating bounce solutions to the Euclidean field equations for gravity coupled to a scalar field theory with two, possibly degenerate, vacua. In these solutions the scalar field crosses the top of the potential barrier $k>1$ times. Using analytic and numerical methods, we examine how the maximum allowed value of $k$ depends on the parameters of the theory. For a wide class of potentials $k_{\rm max}$ is determined by the value of the second derivative of the scalar field potential at the top of the barrier. However, in other cases, such as potentials with relatively flat barriers, the determining parameter appears instead to be the value of this second derivative averaged over the width of the barrier. As a byproduct, we gain additional insight into the conditions under which a Coleman-De Luccia bounce exists. We discuss the physical interpretation of these solutions and their implications for vacuum tunneling transitions in de Sitter spacetime.Comment: 31 pages, 11 figure

CO chemisorption on Ir(111)

The adsorption of carbon monoxide on the (111) crystallographic orientation of iridium both at and below room temperature has been investigated using both low‐energy electron diffraction (LEED) and thermal desorption mass spectrometry. At room temperature, CO adsorbs rapidly resulting in the appearance of a faint (√3×√3) R30° LEED pattern after only approximately 1.3×10^(−6) Torr s (1.72×10^(−4) Pa s) exposure. Upon further exposure to CO, the intensity of the overlayer LEED beams initially increases, but then decreases passing through a maximum at an exposure of approximately 2.4×10^(−6) Torr s (3.2×10^(−4) Pa s). By an exposure of 10^(−5) Torr s (1.3×10^(−3) Pa s) each of the (rather dim and diffuse) overlayer beams has split into two beams. These beams then move toward the substrate beams with increasing CO surface coverage, until near saturation coverage the angle between the split overlayer beams subtended at the (00) beam is greater than 30°

WETLANDS, WILDLIFE, AND WATER QUALITY: TARGETING AND TRADE OFFS

Cost-effective targeting of conservation activities has only recently been addressed by economists. Most work to date has focused on finding the best locations to set aside land for the protection of biodiversity. An economic approach to the problem, where biodiversity reserve networks are delineated to maximize the number of species protected subject to a budget constraint, has been shown to be much more cost-effective than the standard approach, where reserve networks are delineated subject to an area constraint, ignoring differences in costs across sites. This paper is among the first to use spatially explicit models of production functions for ecosystem services in an optimization framework for prioritizing sites for wetlands restoration. Tradeoffs between two classes of environmental benefits from wetlands restoration, habitat, and water quality were assessed in the Central Valley of California. Habitat benefits were estimated by a count regression model that relates breeding mallard abundances to the configuration of land use types in the study area, and water quality benefits were estimated by a spatially distributed model of nonpoint source pollution and nutrient attenuation in wetlands. Two decision scenarios were analyzed. In the first scenario the optimal configuration of restoration activity was determined for a small watershed, and in the second scenario sites were selected from those offered for enrollment in an easement program throughout the valley. The results reveal the potential for gains in effectiveness from spatial targeting, and they suggest that there will be substantial tradeoffs between environmental benefits. Maximizing habitat quality in the small watershed yielded a 34% increase in mallard abundance and a 3% decrease in nitrogen loads to the river. In contrast, maximizing water quality resulted in a 25% decrease in nitrogen loads and a 2% increase in mallard abundance. Qualitatively similar results were obtained when sites were selected from a set of offered sites throughout the valley, but the tradeoffs were not as severe. The results also suggest that at traditional funding levels the Wetlands Reserve Program in California could reduce nitrogen loads to rivers by approximately 29,000 kg and increase total mallard abundance in the breeding season by approximately 150 individuals throughout the Central Valley in a given year.Resource /Energy Economics and Policy,

Solution of 3-dimensional time-dependent viscous flows. Part 2: Development of the computer code

There is considerable interest in developing a numerical scheme for solving the time dependent viscous compressible three dimensional flow equations to aid in the design of helicopter rotors. The development of a computer code to solve a three dimensional unsteady approximate form of the Navier-Stokes equations employing a linearized block emplicit technique in conjunction with a QR operator scheme is described. Results of calculations of several Cartesian test cases are presented. The computer code can be applied to more complex flow fields such as these encountered on rotating airfoils

Solution of 3-dimensional time-dependent viscous flows. Part 3: Application to turbulent and unsteady flows

A numerical scheme is developed for solving the time dependent, three dimensional compressible viscous flow equations to be used as an aid in the design of helicopter rotors. In order to further investigate the numerical procedure, the computer code developed to solve an approximate form of the three dimensional unsteady Navier-Stokes equations employing a linearized block implicit technique in conjunction with a QR operator scheme is tested. Results of calculations are presented for several two dimensional boundary layer flows including steady turbulent and unsteady laminar cases. A comparison of fourth order and second order solutions indicate that increased accuracy can be obtained without any significant increases in cost (run time). The results of the computations also indicate that the computer code can be applied to more complex flows such as those encountered on rotating airfoils. The geometry of a symmetric NACA four digit airfoil is considered and the appropriate geometrical properties are computed

Annealing of radiation damage in low resistivity silicon solar cells

The reduction of the temperatures required to restore cell performance after irradiation was investigated with emphasis on the annealing characteristics of two groups of cells containing different amounts of oxygen and carbon. Examination of defect behavior in irradiated boron doped silicon leads to the tentative conclusion that further reduction in annealing temperature could be achieved by decreasing the carbon concentration and either neutralizing the divacancy and/or minimizing its formation as a result of irradiation. A significant reduction in the temperature required to remove radiation induced degradation in 0.1 ohm centimeter silicon solar cells was achieved

Reverse annealing in radiation-damaged, silicon solar cells

In order to understand the results in terms of properties of the radiation induced defects, a combination of diffusion length measurements and defect data obtained from Deep Level Transient Spectroscopy were used. The results indicate that the defect at E sub v + 0.30 eV is responsible for the observed reversed annealing. The defect was identified as a boron-oxygen vacancy complex. This identification is a guide to processing efforts aimed at increasing the concentration of these radiation induced defects

Radiation damage annealing mechanisms and possible low temperature annealing in silicon solar cells

The defect responsible for reverse annealing in 2 ohm/cm n(+)/p silicon solar cells was identified. This defect, with energy level at e sub v + 0.30 eV was tentatively identified as a boron oxygen-vacancy complex. Results indicate that its removal could result in significant annealing for 2 ohm/cm and lower resistivity cells at temperatures as low as 200 C. These results were obtained by use of an expression derived from the Shockley-Read-Hall recombination theory which relates measured diffusion length ratios to relative defect concentrations and electron capture cross sections. The relative defect concentrations and one of the required capture cross sections are obtained from Deep Level Transient Spectroscopy. Four additional capture cross sections are obtained using diffusion length data and data from temperature dependent lifetime studied. These calculated results are in reasonable agreement with experimental data