4,943 research outputs found
Topology in Physics - A Perspective
This article, written in honor of Fritz Rohrlich, briefly surveys the role of
topology in physics.Comment: 16pp, 2 figures included (encapsulated postscript
Unparticle physics in top pair signals at the LHC and ILC
We study the effects of unparticle physics in the pair productions of top
quarks at the LHC and ILC. By considering vector, tensor and scalar unparticle
operators, as appropriate, we compute the total cross sections for pair
production processes depending on scale dimension d_{\U}. We find that the
existence of unparticles would lead to measurable enhancements on the SM
predictions at the LHC. In the case of ILC this may become two orders of
magnitude larger than that of SM, for smaller values of d_\U, a very striking
signal for unparticles.Comment: 19 pages, 9 figures, analysis for ILC has been adde
NNLO phase space master integrals for two-to-one inclusive cross sections in dimensional regularization
We evaluate all phase space master integrals which are required for the total
cross section of generic 2 -> 1 processes at NNLO as a series expansion in the
dimensional regulator epsilon. Away from the limit of threshold production, our
expansion includes one order higher than what has been available in the
literature. At threshold, we provide expressions which are valid to all orders
in terms of Gamma functions and hypergeometric functions. These results are a
necessary ingredient for the renormalization and mass factorization of
singularities in 2 -> 1 inclusive cross sections at NNNLO in QCD.Comment: 37 pages, plus 3 ancillary files containing analytic expressions in
Maple forma
Unparticle Physics in Single Top Signals
We study the single production of top quarks in and
collisions in the context of unparticle physics through the Flavor Violating
(FV) unparticle vertices and compute the total cross sections for single top
production as functions of scale dimension d_{\U}. We find that among all,
LHC is the most promising facility to probe the unparticle physics via single
top quark production processes.Comment: 14 pages, 10 figure
Submerged turbulence detection with optical satellites
During fall periods in 2002, 2003 and 2004 three major oceanographic
expeditions were carried out in Mamala Bay, Hawaii. These were part of the RASP
Remote Anthropogenic Sensing Program. Ikonos and Quickbird optical satellite
images of sea surface glint revealed ~100 m spectral anomalies in km^2
averaging patches in regions leading from the Honolulu Sand Island Municipal
Outfall diffuser to distances up to 20 km. To determine the mechanisms behind
this phenomenon, the RASP expeditions monitored the waters adjacent to the
outfall with an array of hydrographic, optical and turbulence microstructure
sensors in anomaly and ambient background regions. Drogue tracks and mean
turbulence parameters for 2x10^4 microstructure patches were analyzed to
understand complex turbulence, fossil turbulence and zombie turbulence
near-vertical internal wave transport processes. The dominant mechanism appears
to be generic to stratified natural fluids including planet and star
atmospheres and is termed beamed zombie turbulence maser action (BZTMA). Most
of the bottom turbulent kinetic energy is converted to ~100 m fossil turbulence
waves. These activate secondary (zombie) turbulence in outfall fossil
turbulence patches that transmit heat, mass, chemical species, momentum and
information vertically to the sea surface for detection in an efficient maser
action. The transport is beamed in intermittent mixing chimneys.Comment: 8 pages, 7 figures, SPIE Optics+Photonics 2007 Coastal Ocean Remote
Sensing Aug. 27, San Diego, CA, see http://sdcc3.ucsd.edu/~ir11
Recommended from our members
Scope and Predictive Genetic/Phenotypic Signatures of Bicarbonate (NaHCO3) Responsiveness and β-Lactam Sensitization in Methicillin-Resistant Staphylococcus aureus.
Addition of sodium bicarbonate (NaHCO3) to standard antimicrobial susceptibility testing medium reveals certain methicillin-resistant Staphylococcus aureus (MRSA) strains to be highly susceptible to β-lactams. We investigated the prevalence of this phenotype (NaHCO3 responsiveness) to two β-lactams among 58 clinical MRSA bloodstream isolates. Of note, ∼75% and ∼36% of isolates displayed the NaHCO3 responsiveness phenotype to cefazolin (CFZ) and oxacillin (OXA), respectively. Neither intrinsic β-lactam MICs in standard Mueller-Hinton broth (MHB) nor population analysis profiles were predictive of this phenotype. Several genotypic markers (clonal complex 8 [CC8]; agr I and spa t008) were associated with NaHCO3 responsiveness for OXA
4/3-Law of Granular Particles Flowing through a Vertical Pipe
Density waves of granular material (sand) flowing through a vertical pipe
have been investigated. Clear density waves emerge when the cock attached to
bottom end of the pipe is closed. The FFT power spectra were found to show a
stable power-law form The value of the exponent was
evaluated as . We also introduce a simple one-dimensional
model which reproduces from both simulation and theoretical
analysis. (to be published in Phys.Rev.Lett.)Comment: 4 pages, 4 figures, a style fil
Supergrassmannian and large N limit of quantum field theory with bosons and fermions
We study a large N_{c} limit of a two-dimensional Yang-Mills theory coupled
to bosons and fermions in the fundamental representation. Extending an approach
due to Rajeev we show that the limiting theory can be described as a classical
Hamiltonian system whose phase space is an infinite-dimensional
supergrassmannian. The linear approximation to the equations of motion and the
constraint yields the 't Hooft equations for the mesonic spectrum. Two other
approximation schemes to the exact equations are discussed.Comment: 24 pages, Latex; v.3 appendix added, typos corrected, to appear in
JM
Near-Infrared Molecular Hydrogen Emission from the Central Regions of Galaxies: Regulated Physical Conditions in the Interstellar Medium
The central regions of many interacting and early-type spiral galaxies are
actively forming stars. This process affects the physical and chemical
properties of the local interstellar medium as well as the evolution of the
galaxies. We observed near-infrared H2 emission lines: v=1-0 S(1), 3-2 S(3),
1-0 S(0), and 2-1 S(1) from the central ~1 kpc regions of the archetypical
starburst galaxies, M82 and NGC 253, and the less dramatic but still vigorously
star-forming galaxies, NGC 6946 and IC 342. Like the far-infrared continuum
luminosity, the near-infrared H2 emission luminosity can directly trace the
amount of star formation activity because the H2 emission lines arise from the
interaction between hot and young stars and nearby neutral clouds. The observed
H2 line ratios show that both thermal and non-thermal excitation are
responsible for the emission lines, but that the great majority of the
near-infrared H2 line emission in these galaxies arises from energy states
excited by ultraviolet fluorescence. The derived physical conditions, e.g.,
far-ultraviolet radiation field and gas density, from [C II] and [O I] lines
and far-infrared continuum observations when used as inputs to
photodissociation models, also explain the luminosity of the observed H2 v=1-0
S(1) line. The ratio of the H2 v=1-0 S(1) line to far-IR continuum luminosity
is remarkably constant over a broad range of galaxy luminosities; L_H2/L_FIR =
about 10^{-5}, in normal late-type galaxies (including the Galactic center), in
nearby starburst galaxies, and in luminous IR galaxies (LIRGs: L_FIR > 10^{11}
L_sun). Examining this constant ratio in the context of photodissociation
region models, we conclude that it implies that the strength of the incident UV
field on typical molecular clouds follows the gas density at the cloud surface.Comment: Accepted for ApJ, 24 pages, 17 figures, for complete PDF file, see
http://kao.re.kr/~soojong/mypaper/2004_pak_egh2.pd
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