20,141 research outputs found
Almost-Commutative Geometries Beyond the Standard Model III: Vector Doublets
We will present a new extension of the standard model of particle physics in
its almostcommutative formulation. This extension has as its basis the algebra
of the standard model with four summands [11], and enlarges only the particle
content by an arbitrary number of generations of left-right symmetric doublets
which couple vectorially to the U(1)_YxSU(2)_w subgroup of the standard model.
As in the model presented in [8], which introduced particles with a new colour,
grand unification is no longer required by the spectral action. The new model
may also possess a candidate for dark matter in the hundred TeV mass range with
neutrino-like cross section
Almost-Commutative Geometries Beyond the Standard Model II: New Colours
We will present an extension of the standard model of particle physics in its
almost-commutative formulation. This extension is guided by the minimal
approach to almost-commutative geometries employed in [13], although the model
presented here is not minimal itself.
The corresponding almost-commutative geometry leads to a Yang-Mills-Higgs
model which consists of the standard model and two new fermions of opposite
electro-magnetic charge which may possess a new colour like gauge group. As a
new phenomenon, grand unification is no longer required by the spectral action.Comment: Revised version for publication in J.Phys.A with corrected Higgs
masse
The Inverse Seesaw Mechanism in Noncommutative Geometry
In this publication we will implement the inverse Seesaw mechanism into the
noncommutative framework on the basis of the AC-extension of the Standard
Model. The main difference to the classical AC model is the chiral nature of
the AC fermions with respect to a U(1) extension of the Standard Model gauge
group. It is this extension which allows us to couple the right-handed
neutrinos via a gauge invariant mass term to left-handed A-particles. The
natural scale of these gauge invariant masses is of the order of 10^17 GeV
while the Dirac masses of the neutrino and the AC-particles are generated
dynamically and are therefore much smaller (ca. 1 GeV to 10^6 GeV). From this
configuration a working inverse Seesaw mechanism for the neutrinos is obtained
Research and Development Expenditures of Innovative Enterprises in the Time of Crisis
In an analysed group of enterprises the smallest "resistance" to crisis was observed in American companies. The enterprises from the EU also reduced research and development expenditures but the pace of a fall in these expenditures was smaller than in the case of American companies.W badanej zbiorowości przedsiębiorstw najmniejszą "odporność" na kryzys wykazaly firmy amerykańskie. Firmy wywodzące się z UE również zanotowaly zmniejszenie nakladów na badania i rozwój, jednak tempo spadku nakladów badawczo-rozwojowych bylo tu mniejsze niż w przypadku firm amerykańskich
Almost-Commutative Geometries Beyond the Standard Model
In [7-9] and [10] the conjecture is presented that almost-commutative
geometries, with respect to sensible physical constraints, allow only the
standard model of particle physics and electro-strong models as
Yang-Mills-Higgs theories. In this publication a counter example will be given.
The corresponding almost-commutative geometry leads to a Yang-Mills-Higgs
model which consists of the standard model of particle physics and two new
fermions of opposite electro-magnetic charge. This is the second
Yang-Mills-Higgs model within noncommutative geometry, after the standard
model, which could be compatible with experiments. Combined to a hydrogen-like
composite particle these new particles provide a novel dark matter candidate
Making financial markets safer for consumers: lessons from consumer goods markets and beyond
In the wake of the mortgage meltdown, policymakers are discussing how best to protect consumers in financial product markets.Consumer protection ; Financial markets
A Cryogenic Infrared Calibration Target
A compact cryogenic calibration target is presented that has a peak diffuse
reflectance, , from m).
Upon expanding the spectral range under consideration to m) the observed performance gracefully degrades to at the band edges. In the implementation described, a
high-thermal-conductivity metallic substrate is textured with a pyramidal
tiling and subsequently coated with a thin lossy dielectric coating that
enables high absorption and thermal uniformity across the target. The resulting
target assembly is lightweight, has a low-geometric profile, and has survived
repeated thermal cycling from room temperature to K. Basic design
considerations, governing equations, and test data for realizing the structure
described are provided. The optical properties of selected absorptive materials
-- Acktar Fractal Black, Aeroglaze Z306, and Stycast 2850 FT epoxy loaded with
stainless steel powder -- are characterized and presented
Optimal control of electromagnetic field using metallic nanoclusters
The dielectric properties of metallic nanoclusters in the presence of an
applied electromagnetic field are investigated using non-local linear response
theory. In the quantum limit we find a non-trivial dependence of the induced
field and charge distribution on the spatial separation between the clusters
and on the frequency of the driving field. Using a genetic algorithm, these
quantum functionalities are exploited to custom-design sub-wavelength lenses
with a frequency controlled switching capability.Comment: accepted for publication in New Journal of Physic
A virtual world of paleontology
Computer-aided visualization and analysis of fossils has revolutionized the study of extinct organisms. Novel techniques allow fossils to be characterized in three dimensions and in unprecedented detail. This has enabled paleontologists to gain important insights into their anatomy, development, and preservation. New protocols allow more objective reconstructions of fossil organisms, including soft tissues, from incomplete remains. The resulting digital reconstructions can be used in functional analyses, rigorously testing long-standing hypotheses regarding the paleobiology of extinct organisms. These approaches are transforming our understanding of long-studied fossil groups, and of the narratives of organismal and ecological evolution that have been built upon them
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