1,065 research outputs found
To be or not to be? Magnetic monopoles in non-abelian gauge theories
Magnetic monopoles form an inspiring chapter of theoretical physics, covering
a variety of surprising subjects. We review their role in non-abelian gauge
theories. An expose of quite exquisite physics derived from a hypothetical
particle species, because the fact remains that in spite of ever more tempting
arguments from theory, monopoles have never reared their head in experiment.
For many relevant particulars, references to the original literature are
provided.Comment: 34 pages, 7 figures, Contribution to "Fifty Years of Yang- Mills
Theory", edited by G. 't Hooft. Some extra references have been added in the
revised versio
The modular S-matrix as order parameter for topological phase transitions
We study topological phase transitions in discrete gauge theories in two
spatial dimensions induced by the formation of a Bose condensate. We analyse a
general class of euclidean lattice actions for these theories which contain one
coupling constant for each conjugacy class of the gauge group. To probe the
phase structure we use a complete set of open and closed anyonic string
operators. The open strings allow one to determine the particle content of the
condensate, whereas the closed strings enable us to determine the matrix
elements of the modular -matrix, also in the broken phase. From the measured
broken -matrix we may read off the sectors that split or get identified in
the broken phase, as well as the sectors that are confined. In this sense the
modular -matrix can be employed as a matrix valued non-local order parameter
from which the low-energy effective theories that occur in different regions of
parameter space can be fully determined.
To verify our predictions we studied a non-abelian anyon model based on the
quaternion group of order eight by Monte Carlo simulation. We
probe part of the phase diagram for the pure gauge theory and find a variety of
phases with magnetic condensates leading to various forms of (partial)
confinement in complete agreement with the algebraic breaking analysis. Also
the order of various transitions is established.Comment: 37 page
More on core instabilities of magnetic monopoles
In this paper we present new results on the core instability of the 't Hooft
Polyakov monopoles we reported on before. This instability, where the spherical
core decays in a toroidal one, typically occurs in models in which charge
conjugation is gauged. In this paper we also discuss a third conceivable
configuration denoted as ``split core'', which brings us to some details of the
numerical methods we employed. We argue that a core instability of 't Hooft
Polyakov type monopoles is quite a generic feature of models with charged Higgs
particles.Comment: Latex, 15 pages, 6 figures; published versio
News from the Virasoro algebra
It is shown that the local quantum field theory of the chiral energy-
momentum tensor with central charge coincides with the gauge invariant
subtheory of the chiral current algebra at level 1, where the gauge
group is the global symmetry. At higher level, the same scheme gives
rise to -algebra extensions of the Virasoro algebra.Comment: 4 pages, Latex, DESY 93-11
An Intelligent Analysis of Crime through Newspaper Articles - Clustering and Classification
Crime analysis is one of the most important activities of the majority of the intelligent and law enforcement organizations all over the world. Thus, it seems necessary to study reasons, factors and relations between occurrence of different crimes and finding the most appropriate ways to control and avoid more crimes. A major challenge faced by most of the law enforcement and intelligence organizations is efficiently and accurately analyzing the growing volumes of crime related data. The vast geographical diversity and the complexity of crime patterns have made the analyzing and recording of crime data more difficult. This paper presents an intelligent crime analysis system which is designed to overcome the above mentioned problems. Data mining is used extensively in terms of analysis, investigation and discovery of patterns for occurrence of different crimes. The proposed system is a web-based system which performs crime analysis through news articles. In this paper we use a clustering/ classification based model to automatically group the retrieved documents into a list of meaningful categories. The data mining techniques are used to analyze the web data
Fourier transform and the Verlinde formula for the quantum double of a finite group
A Fourier transform S is defined for the quantum double D(G) of a finite
group G. Acting on characters of D(G), S and the central ribbon element of D(G)
generate a unitary matrix representation of the group SL(2,Z). The characters
form a ring over the integers under both the algebra multiplication and its
dual, with the latter encoding the fusion rules of D(G). The Fourier transform
relates the two ring structures. We use this to give a particularly short proof
of the Verlinde formula for the fusion coefficients.Comment: 15 pages, small errors corrected and references added, version to
appear in Journal of Physics
The Mn site in Mn-doped Ga-As nanowires: an EXAFS study
We present an EXAFS study of the Mn atomic environment in Mn-doped GaAs
nanowires. Mn doping has been obtained either via the diffusion of the Mn used
as seed for the nanowire growth or by providing Mn during the growth of
Au-induced wires. As a general finding, we observe that Mn forms chemical bonds
with As but is not incorporated in a substitutional site. In Mn-induced GaAs
wires, Mn is mostly found bonded to As in a rather disordered environment and
with a stretched bond length, reminiscent of that exhibited by MnAs phases. In
Au-seeded nanowires, along with stretched Mn-As coordination we have found the
presence of Mn in a Mn-Au intermetallic compound.Comment: This is an author-created, un-copyedited version of an article
accepted for publication in Semiconductor Science and Technology. IOP
Publishing Ltd is not responsible for any errors or omissions in this version
of the manuscript or any version derived from it. The definitive
publisher-authenticated version is available online at
doi:10.1088/0268-1242/27/8/08500
Aberrant CBFA2T3B gene promoter methylation in breast tumors
BACKGROUND: The CBFA2T3 locus located on the human chromosome region 16q24.3 is frequently deleted in breast tumors. CBFA2T3 gene expression levels are aberrant in breast tumor cell lines and the CBFA2T3B isoform is a potential tumor suppressor gene. In the absence of identified mutations to further support a role for this gene in tumorigenesis, we explored whether the CBFA2T3B promoter region is aberrantly methylated and whether this correlates with expression. RESULTS: Aberrant hypo and hypermethylation of the CBFA2T3B promoter was detected in breast tumor cell lines and primary breast tumor samples relative to methylation index interquartile ranges in normal breast counterpart and normal whole blood samples. A statistically significant inverse correlation between aberrant CBFA2T3B promoter methylation and gene expression was established. CONCLUSION: CBFA2T3B is a potential breast tumor suppressor gene affected by aberrant promoter methylation and gene expression. The methylation levels were quantitated using a second-round real-time methylation-specific PCR assay. The detection of both hypo and hypermethylation is a technicality regarding the methylation methodology.Anthony J Bais, Alison E Gardner, Olivia LD McKenzie, David F Callen, Grant R Sutherland, and Gabriel Kremmidioti
Nested Topological Order
We introduce the concept of nested topological order in a class of exact
quantum lattice Hamiltonian models with non-abelian discrete gauge symmetry.
The topological order present in the models can be partially destroyed by
introducing a gauge symmetry reduction mechanism. When symmetry is reduced in
several islands only, this imposes boundary conditions to the rest of the
system giving rise to topological ground state degeneracy. This degeneracy is
related to the existence of topological fluxes in between islands or,
alternatively, hidden charges at islands. Additionally, island deformations
give rise to an extension of topological quantum computation beyond
quasiparticles.Comment: revtex4, 4 page
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