522 research outputs found
N=2 central charge superspace and a minimal supergravity multiplet
We extend the notion of central charge superspace to the case of local
supersymmetry. Gauged central charge transformations are identified as
diffeomorphisms at the same footing as space-time diffeomorphisms and local
supersymmetry transformations. Given the general structure we then proceed to
the description of a particular vector-tensor supergravity multiplet of 24+24
components, identified by means of rather radical constraints
An overview of new supersymmetric gauge theories with 2-form gauge potentials
An overview of new 4d supersymmetric gauge theories with 2-form gauge
potentials constructed by various authors during the past five years is given.
The key role of three particular types of interaction vertices is emphasized.
These vertices are used to develop a connecting perspective on the new models
and to distinguish between them. One example is presented in detail to
illustrate characteristic features of the models. A new result on couplings of
2-form gauge potentials to Chern-Simons forms is presented.Comment: 11 pages; to appear in the proceedings of NATO ARW "Noncommutative
structures in mathematics and physics" (Kiev 09/00); table in section 3
correcte
Massive gravity from descent equations
Both massless and massive gravity are derived from descent equations
(Wess-Zumino consistency conditions). The massive theory is a continuous
deformation of the massless one.Comment: 8 pages, no figur
Superform formulation for vector-tensor multiplets in conformal supergravity
The recent papers arXiv:1110.0971 and arXiv:1201.5431 have provided a
superfield description for vector-tensor multiplets and their Chern-Simons
couplings in 4D N = 2 conformal supergravity. Here we develop a superform
formulation for these theories. Furthermore an alternative means of gauging the
central charge is given, making use of a deformed vector multiplet, which may
be thought of as a variant vector-tensor multiplet. Its Chern-Simons couplings
to additional vector multiplets are also constructed. This multiplet together
with its Chern-Simons couplings are new results not considered by de Wit et al.
in hep-th/9710212.Comment: 28 pages. V2: Typos corrected and references updated; V3: References
updated and typo correcte
Perturbative Gravity in the Causal Approach
Quantum theory of the gravitation in the causal approach is studied up to the
second order of perturbation theory. We prove gauge invariance and
renormalizability in the second order of perturbation theory for the pure
gravity system (massless and massive). Then we investigate the interaction of
massless gravity with matter (described by scalars and spinors) and massless
Yang-Mills fields. We obtain a difference with respect to the classical field
theory due to the fact that in quantum field theory one cannot enforce the
divergenceless property on the vector potential and this spoils the
divergenceless property of the usual energy-momentum tensor. To correct this
one needs a supplementary ghost term in the interaction Lagrangian.Comment: 50 pages, no figures, some changes in the last sectio
Metafora: A Web-based Platform for Learning to Learn Together in Science and Mathematics
This paper presents Metafora, both a platform for integrated tools as well as an emerging pedagogy for supporting Learning to Learn Together in science and mathematics education. Our goal is to design technology that brings education to a higher level; a level where students not only learn a subject matter, but also gain a set of critical skills needed to engage in and self-regulate collaborative learning experiences in science and math education. We first discuss the core skills we hope students will gain as they learn to learn together. We then present our design and implementation that can achieve this goal; a platform and pedagogy we have developed to support the learning of these skills. Finally, we present an example use of our system based on results from pilot studies that demonstrates interaction with the platform, and potential benefits and limitations of the tools in promoting the associated skills
Indoor Calibration using Segment Chains
International audienceIn this paper, we present a new method for line segments matching for indoor reconstruction. Instead of matching individual seg- ments via a descriptor like most methods do, we match segment chains that have a distinctive topology using a dynamic programing formulation. Our method relies solely on the geometric layout of the segment chain and not on photometric or color profiles. Our tests showed that the presented method is robust and manages to produce calibration information even under a drastic change of viewpoint
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