371 research outputs found
Symmetries of noncommutative scalar field theory
We investigate symmetries of the scalar field theory with harmonic term on
the Moyal space with euclidean scalar product and general symplectic form. The
classical action is invariant under the orthogonal group if this group acts
also on the symplectic structure. We find that the invariance under the
orthogonal group can be restored also at the quantum level by restricting the
symplectic structures to a particular orbit.Comment: 12 pages, revised versio
Connes distance by examples: Homothetic spectral metric spaces
We study metric properties stemming from the Connes spectral distance on
three types of non compact noncommutative spaces which have received attention
recently from various viewpoints in the physics literature. These are the
noncommutative Moyal plane, a family of harmonic Moyal spectral triples for
which the Dirac operator squares to the harmonic oscillator Hamiltonian and a
family of spectral triples with Dirac operator related to the Landau operator.
We show that these triples are homothetic spectral metric spaces, having an
infinite number of distinct pathwise connected components. The homothetic
factors linking the distances are related to determinants of effective Clifford
metrics. We obtain as a by product new examples of explicit spectral distance
formulas. The results are discussed.Comment: 23 pages. Misprints corrected, references updated, one remark added
at the end of the section 3. To appear in Review in Mathematical Physic
Vortex in Maxwell-Chern-Simons models coupled to external backgrounds
We consider Maxwell-Chern-Simons models involving different non-minimal
coupling terms to a non relativistic massive scalar and further coupled to an
external uniform background charge. We study how these models can be
constrained to support static radially symmetric vortex configurations
saturating the lower bound for the energy. Models involving Zeeman-type
coupling support such vortices provided the potential has a "symmetry breaking"
form and a relation between parameters holds. In models where minimal coupling
is supplemented by magnetic and electric field dependant coupling terms, non
trivial vortex configurations minimizing the energy occur only when a non
linear potential is introduced. The corresponding vortices are studied
numericallyComment: LaTeX file, 2 figure
Quantum Hall Conductivity in a Landau Type Model with a Realistic Geometry
In this paper, we revisit some quantum mechanical aspects related to the
Quantum Hall Effect. We consider a Landau type model, paying a special
attention to the experimental and geometrical features of Quantum Hall
experiments. The resulting formalism is then used to compute explicitely the
Hall conductivity from a Kubo formula.Comment: LaTeX, 1 eps figur
Global quantum Hall phase diagram from visibility diagrams
We propose a construction of a global phase diagram for the quantum Hall
effect. This global phase diagram is based on our previous constructions of
visibility diagrams in the context of the Quantum Hall Effect. The topology of
the phase diagram we obtain is in good agreement with experimental observations
(when the spin effect can be neglected). This phase diagram does not show
floating.Comment: LaTeX2e, 9 pages, 5 eps figure
Correlation of Aggregatibacter actinomycetemcomitans Detection with Clinical/Immunoinflammatory Profile of Localized Aggressive Periodontitis Using a 16S rRNA Microarray Method: A Cross-Sectional Study
Objective
The objective of this study was to determine whether the detection of Aggregatibacter actinomycetemcomitans (Aa) correlates with the clinical and immunoinflammatory profile of Localized Aggressive Periodontitis (LAP), as determined by by 16S rRNA gene-based microarray. Subjects and Methods
Subgingival plaque samples from the deepest diseased site of 30 LAP patients [PD ≥ 5 mm, BoP and bone loss] were analyzed by 16S rRNA gene-based microarrays. Gingival crevicular fluid (GCF) samples were analyzed for 14 cyto/chemokines. Peripheral blood was obtained and stimulated in vitro with P.gingivalis and E.coli to evaluate inflammatory response profiles. Plasma lipopolysaccharide (LPS) levels were also measured. Results
Aa was detected in 56% of LAP patients and was shown to be an indicator for different bacterial community structures (p\u3c0.01). Elevated levels of pro-inflammatory cyto/chemokines were detected in LPS-stimulated blood samples in both Aa-detected and Aa-non-detected groups (p\u3e0.05). Clinical parameters and serum LPS levels were similar between groups. However, Aa-non-detected GCF contained higher concentration of IL-8 than Aa-detected sites (p\u3c0.05). TNFα and IL1β were elevated upon E.coli LPS stimulation of peripheral blood cells derived from patients with Aa-detected sites. Conclusions
Our findings demonstrate that the detection of Aa in LAP affected sites, did not correlate with clinical severity of the disease at the time of sampling in this cross-sectional study, although it did associate with lower local levels of IL-8, a different subgingival bacterial profile and elevated LPS-induced levels of TNFα and IL1β
Non Abelian TQFT and scattering of self dual field configuration
A non-abelian topological quantum field theory describing the scattering of
self-dual field configurations over topologically non-trivial Riemann surfaces,
arising from the reduction of 4-dim self-dual Yang-Mills fields, is introduced.
It is shown that the phase space of the theory can be exactly quantized in
terms of the space of holomorphic structures over stable vector bundles of
degree zero over Riemann surfaces. The Dirac monopoles are particular static
solutions of the field equations. Its relation to topological gravity is
discussed.Comment: 13 pages, Late
Symmetry breaking, conformal geometry and gauge invariance
When the electroweak action is rewritten in terms of SU(2) gauge invariant
variables, the Higgs can be interpreted as a conformal metric factor. We show
that asymptotic flatness of the metric is required to avoid a Gribov problem:
without it, the new variables fail to be nonperturbatively gauge invariant. We
also clarify the relations between this approach and unitary gauge fixing, and
the existence of similar transformations in other gauge theories.Comment: 11 pages. Version 2: typos corrected, discussion of Elitzur's theorem
added. Version to appear in J.Phys.
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