1,753,340 research outputs found
Smooth Bosonization as a Quantum Canonical Transformation
We consider a 1+1 dimensional field theory which contains both a complex
fermion field and a real scalar field. We then construct a unitary operator
that, by a similarity transformation, gives a continuum of equivalent theories
which smoothly interpolate between the massive Thirring model and the
sine-Gordon model. This provides an implementation of smooth bosonization
proposed by Damgaard et al. as well as an example of a quantum canonical
transformation for a quantum field theory.Comment: 20 pages, revte
Stress-Induced Phase Transformations in Shape-Memory Polycrystals
Shape-memory alloys undergo a solid-to-solid phase transformation involving a change of crystal structure. We examine model problems in the scalar setting motivated by the situation when this transformation is induced by the application of stress in a polycrystalline material made of numerous grains of the same crystalline solid with varying orientations. We show that the onset of transformation in a granular polycrystal with homogeneous elasticity is in fact predicted accurately by the so-called Sachs bound based on the ansatz of uniform stress. We also present a simple example where the onset of phase transformation is given by the Sachs bound, and the extent of phase transformation is given by the constant strain Taylor bound. Finally we discuss the stressâstrain relations of the general problem using MiltonâSerkov bounds
Automating the transformation-based analysis of visual languages
The final publication is available at Springer via http://dx.doi.org/10.1007/s00165-009-0114-yWe present a novel approach for the automatic generation of model-to-model transformations given a description of the operational semantics of the source language in the form of graph transformation rules. The approach is geared to the generation of transformations from Domain-Specific Visual Languages (DSVLs) into semantic domains with an explicit notion of transition, like for example Petri nets. The generated transformation is expressed in the form of operational triple graph grammar rules that transform the static information (initial model) and the dynamics (source rules and their execution control structure). We illustrate these techniques with a DSVL in the domain of production systems, for which we generate a transformation into Petri nets. We also tackle the description of timing aspects in graph transformation rules, and its analysis through their automatic translation into Time Petri netsWork sponsored by the Spanish Ministry of Science and Innovation, project METEORIC (TIN2008-02081/TIN) and by the Canadian Natural Sciences and Engineering Research Council (NSERC)
UML to XML-Schema Transformation: a Case Study in Managing Alternative Model Transformations in MDA
In a Model Driven Architecture (MDA) software development process, models are\ud
repeatedly transformed to other models in order to finally achieve a set of models with enough details to implement a system. Generally, there are multiple ways to transform one model into another model. Alternative target models differ in their quality properties and the selection of a particular model is determined on the basis of specific requirements. Software engineers must be able to identify, compare and select the appropriate transformations within the given set of requirements. The current transformation languages used for describing and executing model transformations only provide means to specify the transformations but do not help to identify and select from the alternative transformations. In this paper we propose a process and a set of techniques for constructing a transformation space for a given transformation problem. The process uses a source model, its meta-model and the meta-model of the target as input and generates a transformation space. Every element in that space represents a transformation that produces a result that is an instance of the target meta-model. The requirements that must be fulfilled by the result are captured and represented in a quality model. We explain our approach using an illustrative example for transforming a platform independent model expressed in UML into platform specific models that represent XML schemas. A particular quality model of extensibility is presented in the paper
Matrix Theory in a Constant C Field Background
D0-branes moving in a constant antisymmetric C field are found to be
described by quantum mechanics of the supersymmetric matrix model with a
similarity transformation. Sometimes this similarity transformation is singular
or ill-defined and cannot be ignored. As an example, when there are
non-vanishing C_{-ij} components, we obtain the theory for Dp-branes which is
effectively the noncommutative super Yang-Mills theory. We also briefly discuss
the effects of other non-vanishing components such as C_{+ij} and C_{ijk}.Comment: harvmac, 17 pages, references adde
The strong coupling Kondo lattice model as a Fermi gas
The strong coupling half-filled Kondo lattice model is an important example
of a strongly interacting dense Fermi system for which conventional Fermi gas
analysis has thus far failed. We remedy this by deriving an exact
transformation that maps the model to a dilute gas of weakly interacting
electron and hole quasiparticles that can then be analyzed by conventional
dilute Fermi gas methods. The quasiparticle vacuum is a singlet Mott insulator
for which the quasiparticle dynamics are simple. Since the transformation is
exact, the electron spectral weight sum rules are obeyed exactly. Subtleties in
understanding the behavior of electrons in the singlet Mott insulator can be
reduced to a fairly complicated but precise relation between quasiparticles and
bare electrons. The theory of free quasiparticles can be interpreted as an
exactly solvable model for a singlet Mott insulator, providing an exact model
in which to explore the strong coupling regime of a singlet Kondo insulator.Comment: 10pages, 2 figure
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