6,492 research outputs found
Chiral Green's Functions in Superconformal Field Theory
By solving the Ward identities in a superconformal field theory we find the
unique three-point Green's functions composed of chiral superfields for N =
1,2,3,4 supersymmetry. We show that the N=1 four-point function with R-charge
equal to one is uniquely determined by the Ward identities up to the
specification of four constants. We discuss why chiral Green's functions above
three-points, with total R-charge greater than N, are not uniquely determined.Comment: 32 pages, no figures, LaTeX2e forma
Geological evaluation and applications of ERTS-1 imagery over Georgia
ERTS-1 70mm and 9 x 9 film negatives are being used by conventional and color enhancement methods as a tool for geologic investigation. Geologic mapping and mineral exploration by conventional methods is very difficult in Georgia. Thick soil cover and heavy vegetation cause outcrops of bed rock to be small, rare and obscure. ERTS imagery, and remote sensing in general have helped delineate: (1) major tectonic boundaries; (2) lithologic contacts; (3) foliation trends; (4) topographic lineaments; and (5) faults. The ERTS-1 MSS imagery yields the greatest amount of geologic information on the Piedomont, Blue Ridge, and Valley and Ridge Provinces of Georgia where topography is strongly controlled by the bedrock geology. ERTS imagery, and general remote sensing techniques, have provided us with a powerful tool to assist geologic research; have significantly increased the mapping efficiency of our field geologists; have shown new lineaments associated with known shear and fault zones; have delineated new structural features; have provided a tool to re-evaluate our tectonic history; have helped to locate potential ground water sources and areas of aquifer recharge; have defined areas of geologic hazards; have shown areas of heavy siltation in major reservoirs; and by its close interval repetition, have aided in monitoring surface mine reclamation activities and the environmental protection of our intricate marshland system
Atomic and Molecular Data for Optical Stellar Spectroscopy
High-precision spectroscopy of large stellar samples plays a crucial role for
several topical issues in astrophysics. Examples include studying the chemical
structure and evolution of the Milky Way galaxy, tracing the origin of chemical
elements, and characterizing planetary host stars. Data are accumulating from
instruments that obtain high-quality spectra of stars in the ultraviolet,
optical and infrared wavelength regions on a routine basis. These instruments
are located at ground-based 2- to 10-m class telescopes around the world, in
addition to the spectrographs with unique capabilities available at the Hubble
Space Telescope. The interpretation of these spectra requires high-quality
transition data for numerous species, in particular neutral and singly ionized
atoms, and di- or triatomic molecules. We rely heavily on the continuous
efforts of laboratory astrophysics groups that produce and improve the relevant
experimental and theoretical atomic and molecular data. The compilation of the
best available data is facilitated by databases and electronic infrastructures
such as the NIST Atomic Spectra Database, the VALD database, or the Virtual
Atomic and Molecular Data Centre (VAMDC). We illustrate the current status of
atomic data for optical stellar spectra with the example of the Gaia-ESO Public
Spectroscopic Survey. Data sources for 35 chemical elements were reviewed in an
effort to construct a line list for a homogeneous abundance analysis of up to
100000 stars.Comment: Published 30 April 2015 in Physica Script
Clay Synthesis: Modeling the Uptake of Potassium during Low Temperature Illitization of Smectite
Fe I Oscillator Strengths for the Gaia-ESO Survey
The Gaia-ESO Public Spectroscopic Survey (GES) is conducting a large-scale
study of multi-element chemical abundances of some 100 000 stars in the Milky
Way with the ultimate aim of quantifying the formation history and evolution of
young, mature and ancient Galactic populations. However, in preparing for the
analysis of GES spectra, it has been noted that atomic oscillator strengths of
important Fe I lines required to correctly model stellar line intensities are
missing from the atomic database. Here, we present new experimental oscillator
strengths derived from branching fractions and level lifetimes, for 142
transitions of Fe I between 3526 {\AA} and 10864 {\AA}, of which at least 38
are urgently needed by GES. We also assess the impact of these new data on
solar spectral synthesis and demonstrate that for 36 lines that appear
unblended in the Sun, Fe abundance measurements yield a small line-by-line
scatter (0.08 dex) with a mean abundance of 7.44 dex in good agreement with
recent publications.Comment: Accepted for publication in Mon. Not. R. Astron. So
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