20,533 research outputs found
Detours and Paths: BRST Complexes and Worldline Formalism
We construct detour complexes from the BRST quantization of worldline
diffeomorphism invariant systems. This yields a method to efficiently extract
physical quantum field theories from particle models with first class
constraint algebras. As an example, we show how to obtain the Maxwell detour
complex by gauging N=2 supersymmetric quantum mechanics in curved space. Then
we concentrate on first class algebras belonging to a class of recently
introduced orthosymplectic quantum mechanical models and give generating
functions for detour complexes describing higher spins of arbitrary symmetry
types. The first quantized approach facilitates quantum calculations and we
employ it to compute the number of physical degrees of freedom associated to
the second quantized, field theoretical actions.Comment: 1+35 pages, 1 figure; typos corrected and references added, published
versio
Virtual Braids
In the present paper we give a new method for converting virtual knots and
links to virtual braids. Indeed the braiding method given in this paper is
quite general, and applies to all the categories in which braiding can be
accomplished. We give a unifying topological interpretation of virtuals and
flats (virtual strings) and their isotopies via ribbon surfaces and abstract
link diagrams. We also give reduced presentations for the virtual braid group,
the flat virtual braid group, the welded braid group and several other
categories of braids. The paper includes a discussion of the topological
intepretation of the welded braid group in terms of tubes embedded in
four-space. A sequel to this paper will give a new proof of a Markov Theorem
for virtual braids (and related categories) via the L-move (a technique
pioneered for classical braids and braids in three-manifolds by the second
author).Comment: 31 pages, 22 figures, LaTeX documen
BRST Detour Quantization
We present the BRST cohomologies of a class of constraint (super) Lie
algebras as detour complexes. By giving physical interpretations to the
components of detour complexes as gauge invariances, Bianchi identities and
equations of motion we obtain a large class of new gauge theories. The pivotal
new machinery is a treatment of the ghost Hilbert space designed to manifest
the detour structure. Along with general results, we give details for three of
these theories which correspond to gauge invariant spinning particle models of
totally symmetric, antisymmetric and K\"ahler antisymmetric forms. In
particular, we give details of our recent announcement of a (p,q)-form K\"ahler
electromagnetism. We also discuss how our results generalize to other special
geometries.Comment: 43 pages, LaTeX, added reference
Free singularity path planning of hybrid parallel robot
This paper presents a singularity-free path planning approach for a hybrid parallel robot. The hybrid robot is composed of two well-known parallel robots, a hexapod and a tripod, that are serially connected. In this paper a methodology is developed to avoid singularity configurations of the hybrid parallel robot. Nominal polynomial paths are used for motion of end effector, and the strokes of each actuator is calculated by using the developed inverse kinematic. A MATLAB program has been developed to generate the designed paths, and several poses have been tested in a CAD model of the hybrid parallel robot to validate the feasibility of the path planning approach
Higher Spin Gravitational Couplings and the Yang--Mills Detour Complex
Gravitational interactions of higher spin fields are generically plagued by
inconsistencies. We present a simple framework that couples higher spins to a
broad class of gravitational backgrounds (including Ricci flat and Einstein)
consistently at the classical level. The model is the simplest example of a
Yang--Mills detour complex, which recently has been applied in the mathematical
setting of conformal geometry. An analysis of asymptotic scattering states
about the trivial field theory vacuum in the simplest version of the theory
yields a rich spectrum marred by negative norm excitations. The result is a
theory of a physical massless graviton, scalar field, and massive vector along
with a degenerate pair of zero norm photon excitations. Coherent states of the
unstable sector of the model do have positive norms, but their evolution is no
longer unitary and their amplitudes grow with time. The model is of
considerable interest for braneworld scenarios and ghost condensation models,
and invariant theory.Comment: 19 pages LaTe
Virtual Knot Cobordism
This paper defines a theory of cobordism for virtual knots and studies this
theory for standard and rotational virtual knots and links. Non-trivial
examples of virtual slice knots are given. Determinations of the four-ball
genus of positive virtual knots are given using the results of a companion
paper by the author and Heather Dye and Aaron Kaestner. Problems related to
band-passing are explained, and a theory of isotopy of virtual surfaces is
formulated in terms of a generalization of the Yoshikawa moves.Comment: 32 pages, 43 figures, LaTeX documen
Reconsidering feminisms and the work of Norbert Elias for understanding gender, sport and sport-related activities
This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2008 North West Counties Physical Education Association and SAGE Publications.This paper reconsiders the relationships between feminist perspectives and the figurational/process-sociological perspective of Norbert Elias for understanding gender, sport and sport-related activities. The main aim of the article is to respond to Colwell's claim that there are differences between feminist and figurational approaches to understanding and explaining gender that potentially negate the possibility of being a feminist and figurational sociologist at the same time. The paper makes a contribution to the wider discussions about the adequacy of Elias's work in understanding gender and sport, and the potential of blending feminist and figurational perspectives on sport and gender. It introduces the principles underlying feminist and figurational approaches to sociology. The key features of the ongoing debate about the differences between feminist and figurational approaches are briefly outlined. I reply to Colwell's criticisms of my work and revisit issues surrounding the role of values and evaluation in sociology. Involved-detachment is introduced as a feminist interpretation of Elias's theory of ever changing balances of involvement-detachment. The final part of the paper presents some reflections about working with involved-detachment in specific research on women's involvement in sport-related fitness activities
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