2,539 research outputs found
Noncommutative Field Theories and (Super)String Field Theories
In this lecture notes we explain and discuss some ideas concerning
noncommutative geometry in general, as well as noncommutative field theories
and string field theories. We consider noncommutative quantum field theories
emphasizing an issue of their renormalizability and the UV/IR mixing. Sen's
conjectures on open string tachyon condensation and their application to the
D-brane physics have led to wide investigations of the covariant string field
theory proposed by Witten about 15 years ago. We review main ingredients of
cubic (super)string field theories using various formulations: functional,
operator, conformal and the half string formalisms. The main technical tools
that are used to study conjectured D-brane decay into closed string vacuum
through the tachyon condensation are presented. We describe also methods which
are used to study the cubic open string field theory around the tachyon vacuum:
construction of the sliver state, ``comma'' and matrix representations of
vertices.Comment: 160 pages, LaTeX, 29 EPS figures. Lectures given by I.Ya.Aref'eva at
the Swieca Summer School, Brazil, January 2001; Summer School in Modern
Mathematical Physics, Sokobanja, Yugoslavia, August 2001; Max Born Symposium,
Karpacz, Poland, September, 2001; Workshop "Noncommutative Geometry, Strings
and Renormalization", Leipzig, Germany, September 2001. Typos corrected,
references adde
Pisgah Lava Cave Communication Test: Science Case Study for the Networked Constellations Initiative
As part of the science case study for the Networked Constellations initiative, a team of JPL scientists explore the possibility of a mission to study the lava caves on Mars. Natural caves on Mars and the Moon present a unique opportunity to learn about the planetary geology and to provide a shelter for human explorers. Due to power and communication challenges, a network of assets has significant advantages over a single asset sent inside a cave. However, communication between the assets and the data downlink present significant difficulties due to the presence of rough walls, boulders, and other obstacles with unknown dielectric constant inside a typical cave, disturbing the propagation of the radio waves. A detailed study is needed to establish the limitations of the current communication technologies and to develop requirements for the new communication technology applicable to the cave environment. On May 4 of 2017, Konstantin Belov, Doug Ellison, and Abby Fraeman visited a lava cave in Pisgah, CA. The purpose of the visit was to build a 3D map of the cave, which could be used to create a model of radio wave propagation, and to conduct a series of communication tests using off-the-shelf equipment to verify the in-cave communication challenges. This experiment should be considered as a simple 'proof of concept' and is the subject of this report
Sub-wavelength imaging at infrared frequencies using an array of metallic nanorods
We demonstrate that an array of metallic nanorods enables sub-wavelength
(near-field) imaging at infrared frequencies. Using an homogenization approach,
it is theoretically proved that under certain conditions the incoming radiation
can be transmitted by the array of nanorods over a significant distance with
fairly low attenuation. The propagation mechanism does not involve a resonance
of material parameters and thus the resolution is not strongly affected by
material losses and has wide bandwidth. The sub-wavelength imaging with
resolution by silver rods at 30 THz is demonstrated numerically
using full-wave electromagnetic simulator.Comment: 12 pages, 16 figures, submitted to PR
The evolution operator of the Hartree-type equation with a quadratic potential
Based on the ideology of the Maslov's complex germ theory, a method has been
developed for finding an exact solution of the Cauchy problem for a
Hartree-type equation with a quadratic potential in the class of
semiclassically concentrated functions. The nonlinear evolution operator has
been obtained in explicit form in the class of semiclassically concentrated
functions. Parametric families of symmetry operators have been found for the
Hartree-type equation. With the help of symmetry operators, families of exact
solutions of the equation have been constructed. Exact expressions are obtained
for the quasi-energies and their respective states. The Aharonov-Anandan
geometric phases are found in explicit form for the quasi-energy states.Comment: 23 pege
Lattice analogues of W-algebras and Classical Integrable Equations
We propose a regular way to construct lattice versions of -algebras, both
for quantum and classical cases. In the classical case we write the algebra
explicitly and derive the lattice analogue of Boussinesq equation from the
Hamiltonian equations of motion. Connection between the lattice
Faddeev-Takhtadjan-Volkov algebra [1] and q-deformed Virasoro is also
discussed.Comment: LaTeX, ILG-TMP-93-01, (the problems caused by mailer are fixed
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