483 research outputs found
A Two-loop Test of Buscher's T-duality I
We study the two loop quantum equivalence of sigma models related by
Buscher's T-duality transformation. The computation of the two loop
perturbative free energy density is performed in the case of a certain
deformation of the SU(2) principal sigma model, and its T-dual, using
dimensional regularization and the geometric sigma model perturbation theory.
We obtain agreement between the free energy density expressions of the two
models.Comment: 28 pp, Latex, references adde
Mathematical Modeling of Biofilm Structures Using COMSTAT Data
Mathematical modeling holds great potential for quantitatively describing biofilm growth in presence or absence of chemical agents used to limit or promote biofilm growth. In this paper, we describe a general mathematical/statistical framework that allows for the characterization of complex data in terms of few parameters and the capability to (i) compare different experiments and exposures to different agents, (ii) test different hypotheses regarding biofilm growth and interaction with different agents, and (iii) simulate arbitrary administrations of agents. The mathematical framework is divided to submodels characterizing biofilm, including new models characterizing live biofilm growth and dead cell accumulation; the interaction with agents inhibiting or stimulating growth; the kinetics of the agents. The statistical framework can take into account measurement and interexperiment variation. We demonstrate the application of (some of) the models using confocal microscopy data obtained using the computer program COMSTAT
Constraints on Beta Functions from Duality
We analyze the way in which duality constrains the exact beta function and
correlation length in single-coupling spin systems. A consistency condition we
propose shows very concisely the relation between self-dual points and phase
transitions, and implies that the correlation length must be duality invariant.
These ideas are then tested on the 2-d Ising model, and used towards finding
the exact beta function of the -state Potts model. Finally, a generic
procedure is given for identifying a duality symmetry in other single-coupling
models with a continuous phase transition.Comment: LaTeX, 6 page
Juvenile idiopathic arthritis flare due to rice bodies in the knee of a 10yearold girl
A 10-year-old girl with juvenile idiopathic arthritis in remission presented with a flare of her arthritis. All her joints responded to treatment except the right knee, despite the use of disease-modifying antirheumatic drugs, non-steroidal anti-inflammatory medication and high-dose cortisone. A magnetic resonance imaging scan showed a knee densely packed with rice bodies. After surgical removal of the rice bodies the inflammation settled once again, and the patient remains well on her usual medication
Implicit Regularization and Renormalization of QCD
We apply the Implicit Regularization Technique (IR) in a non-abelian gauge
theory. We show that IR preserves gauge symmetry as encoded in relations
between the renormalizations constants required by the Slavnov-Taylor
identities at the one loop level of QCD. Moreover, we show that the technique
handles divergencies in massive and massless QFT on equal footing.Comment: (11 pages, 2 figures
General Solution of the non-abelian Gauss law and non-abelian analogs of the Hodge decomposition
General solution of the non-abelian Gauss law in terms of covariant curls and
gradients is presented. Also two non-abelian analogs of the Hodge decomposition
in three dimensions are addressed. i) Decomposition of an isotriplet vector
field as sum of covariant curl and gradient with respect to an
arbitrary background Yang-Mills potential is obtained. ii) A decomposition of
the form which involves non-abelian
magnetic field of a new Yang-Mills potential C is also presented. These results
are relevant for duality transformation for non-abelian gauge fields.Comment: 6 pages, no figures, revte
On the equivalence between Implicit Regularization and Constrained Differential Renormalization
Constrained Differential Renormalization (CDR) and the constrained version of
Implicit Regularization (IR) are two regularization independent techniques that
do not rely on dimensional continuation of the space-time. These two methods
which have rather distinct basis have been successfully applied to several
calculations which show that they can be trusted as practical, symmetry
invariant frameworks (gauge and supersymmetry included) in perturbative
computations even beyond one-loop order.
In this paper, we show the equivalence between these two methods at one-loop
order. We show that the configuration space rules of CDR can be mapped into the
momentum space procedures of Implicit Regularization, the major principle
behind this equivalence being the extension of the properties of regular
distributions to the regularized ones.Comment: 16 page
Differential Regularization of Topologically Massive Yang-Mills Theory and Chern-Simons Theory
We apply differential renormalization method to the study of
three-dimensional topologically massive Yang-Mills and Chern-Simons theories.
The method is especially suitable for such theories as it avoids the need for
dimensional continuation of three-dimensional antisymmetric tensor and the
Feynman rules for three-dimensional theories in coordinate space are relatively
simple. The calculus involved is still lengthy but not as difficult as other
existing methods of calculation. We compute one-loop propagators and vertices
and derive the one-loop local effective action for topologically massive
Yang-Mills theory. We then consider Chern-Simons field theory as the large mass
limit of topologically massive Yang-Mills theory and show that this leads to
the famous shift in the parameter . Some useful formulas for the calculus of
differential renormalization of three-dimensional field theories are given in
an Appendix.Comment: 25 pages, 4 figures. Several typewritten errors and inappropriate
arguments are corrected, especially the correct adresses of authors are give
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