8,220 research outputs found
The Elementary Particles as Quantum Knots in Electroweak Theory
We explore a knot model of the elementary particles that is compatible with
electroweak physics. The knots are quantized and their kinematic states are
labelled by , irreducible representations of , where j =
N/2, m = w/2, m' = (r+1)/2 and (N,w,r) designate respectively the number of
crossings, the writhe, and the rotation of the knot. The knot quantum numbers
(N,w,r) are related to the standard isotopic spin quantum numbers
by , where is the hypercharge. In this
model the elementary fermions are low lying states of the quantum trefoil (N=3)
and the gauge bosons are ditrefoils (N=6). The fermionic knots interact by the
emission and absorption of bosonic knots. In this framework we have explored a
slightly modified standard electroweak Lagrangian with a slightly modified
gauge group which agrees closely but not entirely with standard electroweak
theory.Comment: 29 pages; LaTex fil
Weaving aspects into web service orchestrations
Web Service orchestration engines need to be more
open to enable the addition of new behaviours into
service-based applications. In this paper, we illus-
trate how, in a BPEL engine with aspect-weaving ca-
pabilities, a process-driven application based on the
Google Web Service can be dynamically adapted with
new behaviours and hot-fixed to meet unforeseen post-
deployment requirements. Business processes (the ap-
plication skeletons) can be enriched with additional fea-
tures such as debugging, execution monitoring, or an
application-specific GUI.
Dynamic aspects are also used on the processes
themselves to tackle the problem of hot-fixes to long
running processes. In this manner, composing a Web
Service ’on-the-fly’ means weaving its choreography in-
terface into the business process
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Towards an aspect weaving BPEL engine
This position paper proposes the use of dynamic aspects and
the visitor design pattern to obtain a highly configurable and
extensible BPEL engine. Using these two techniques, the
core of this infrastructural software can be customised to
meet new requirements and add features such as debugging,
execution monitoring, or changing to another Web Service
selection policy. Additionally, it can easily be extended to
cope with customer-specific BPEL extensions. We propose
the use of dynamic aspects not only on the engine itself
but also on the workflow in order to tackle the problems of
Web Service hot deployment and hot fixes to long running
processes. In this way, composing aWeb Service "on-the-fly"
means weaving its choreography interface into the workflow
Masses and Interactions of q-Fermionic Knots
The q-electroweak theory suggests a description of elementary particles as
solitons labelled by the irreducible representations of SU_q(2). Since knots
may also be labelled by the irreducible representations of SU_q(2), we study a
model of elementary particles based on a one-to-one correspondence between the
four families of Fermions (leptons, neutrinos, (-1/3) quarks, (2/3) quarks) and
the four simplest knots (trefoils). In this model the three particles of each
family are identified with the ground and first two excited states of their
common trefoil. Guided by the standard electroweak theory we calculate
conditions restricting the masses of the fermions and the interactions between
them.
In its present form the model predicts a fourth generation of fermions as
well as a neutrino spectrum. The same model with q almost equal to 1 is
compatible with the Kobayashi-Maskawa matrix. Depending on the test of these
predictions, the model may be refined.Comment: 40 pages, 2 figures, latex forma
School Food Environments and Policies in U.S. Public Schools
Examines food environments in elementary, middle, and high schools based on seventeen factors, including foods and beverages offered, the availability of vending machines, and how they vary by grade level, location, and other school characteristics
Topographic Mapping of the Quantum Hall Liquid using a Few-Electron Bubble
A scanning probe technique was used to obtain a high-resolution map of the
random electrostatic potential inside the quantum Hall liquid. A sharp metal
tip, scanned above a semiconductor surface, sensed charges in an embedded
two-dimensional electron gas. Under quantum Hall effect conditions, applying a
positive voltage to the tip locally enhanced the 2D electron density and
created a ``bubble'' of electrons in an otherwise unoccupied Landau level. As
the tip scanned along the sample surface, the bubble followed underneath. The
tip sensed the motions of single electrons entering or leaving the bubble in
response to changes in the local 2D electrostatic potential.Comment: 4 pages, 3 JPG figures, Revtex. For additional info and AVI movies,
visit http://electron.mit.edu/st
Consistency analysis of Kaluza-Klein geometric sigma models
Geometric sigma models are purely geometric theories of scalar fields coupled
to gravity. Geometrically, these scalars represent the very coordinates of
space-time, and, as such, can be gauged away. A particular theory is built over
a given metric field configuration which becomes the vacuum of the theory.
Kaluza-Klein theories of the kind have been shown to be free of the classical
cosmological constant problem, and to give massless gauge fields after
dimensional reduction. In this paper, the consistency of dimensional reduction,
as well as the stability of the internal excitations, are analyzed. Choosing
the internal space in the form of a group manifold, one meets no
inconsistencies in the dimensional reduction procedure. As an example, the
SO(n) groups are analyzed, with the result that the mass matrix of the internal
excitations necessarily possesses negative modes. In the case of coset spaces,
the consistency of dimensional reduction rules out all but the stable mode,
although the full vacuum stability remains an open problem.Comment: 13 pages, RevTe
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