11,347 research outputs found
Gravitation as a Super SL(2,C) Gauge Theory
We present a gauge theory of the super SL(2,C) group. The gauge potential is
a connection of the Super SL(2,C) group. A MacDowell-Mansouri type of action is
proposed where the action is quadratic in the Super SL(2,C) curvature and
depends purely on gauge connection. By breaking the symmetry of the Super
SL(2,C) topological gauge theory to SL(2,C), a metric is naturally defined.Comment: 4 pages, Proceedings of the 9th Marcel Grossmann Meeting, Rome, 2-8
July, 200
Quasi-Local "Conserved Quantities"
Using the Noether Charge formulation, we study a perturbation of the
conserved gravitating system. By requiring the boundary term in the variation
of the Hamiltonian to depend only on the symplectic structure, we propose a
general prescription for defining quasi-local ``conserved quantities'' (i.e. in
the situation when the gravitating system has a non-vanishing energy flux).
Applications include energy-momentum and angular momentum at spatial and null
infinity, asymptotically anti-deSitter spacetimes, and thermodynamics of the
isolated horizons.Comment: 4 pages, contribution to the proceedings of the 9th Marcel Grossmann
Meeting; typos correcte
Gravitation as a Supersymmetric Gauge Theory
We propose a gauge theory of gravitation. The gauge potential is a connection
of the Super SL(2,C) group. A MacDowell-Mansouri type of action is proposed
where the action is quadratic in the Super SL(2,C) curvature and depends purely
on gauge connection. By breaking the symmetry of the Super SL(2,C) topological
gauge theory to SL(2,C), a spinor metric is naturally defined. With an
auxiliary anti-commuting spinor field, the theory is reduced to general
relativity. The Hamiltonian variables are related to the ones given by
Ashtekar. The auxiliary spinor field plays the role of Witten spinor in the
positive energy proof for gravitation.Comment: 11 pages, accepted for publication in Physics Letters
Quasi-Local Energy Flux of Spacetime Perturbation
A general expression for quasi-local energy flux for spacetime perturbation
is derived from covariant Hamiltonian formulation using functional
differentiability and symplectic structure invariance, which is independent of
the choice of the canonical variables and the possible boundary terms one
initially puts into the Lagrangian in the diffeomorphism invariant theories.
The energy flux expression depends on a displacement vector field and the
2-surface under consideration. We apply and test the expression in Vaidya
spacetime. At null infinity the expression leads to the Bondi type energy flux
obtained by Lindquist, Schwartz and Misner. On dynamical horizons with a
particular choice of the displacement vector, it gives the area balance law
obtained by Ashtekar and Krishnan.Comment: 8 pages, added appendix, version to appear in Phys. Rev.
Mirror Symmetry, Mirror Map and Applications to Complete Intersection Calabi-Yau Spaces
We extend the discussion of mirror symmetry, Picard-Fuchs equations,
instanton-corrected Yukawa couplings, and the topological one-loop partition
function to the case of complete intersections with higher-dimensional moduli
spaces. We will develop a new method of obtaining the instanton-corrected
Yukawa couplings through a close study of the solutions of the Picard-Fuchs
equations. This leads to closed formulas for the prepotential for the K\"ahler
moduli fields induced from the ambient space for all complete intersections in
non singular weighted projective spaces. As examples we treat part of the
moduli space of the phenomenologically interesting three-generation models that
are found in this class. We also apply our method to solve the simplest model
in which a topology change was observed and discuss examples of complete
intersections in singular ambient spaces.Comment: 50 page
A method to define a minimum-phase transfer function within the bounded region of phase-gain specifications
Method to define minimum phase transfer function within bounded region of phase gain specifications at several discrete frequencie
Information on the structure of the a1 from tau decay
The decay is analysed using different methods to
account for the resonance structure, which is usually ascribed to the a1. One
scenario is based on the recently developed techniques to generate axial-vector
resonances dynamically, whereas in a second calculation the a1 is introduced as
an explicit resonance. We investigate the influence of different assumptions on
the result. In the molecule scenario the spectral function is described
surprisingly well by adjusting only one free parameter. This result can be
systematically improved by adding higher order corrections to the iterated
Weinberg-Tomozawa interaction. Treating the a1 as an explicit resonance on the
other hand leads to peculiar properties
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