842 research outputs found

    Geometric Gravitational Forces on Particles Moving in a Line

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    In two-dimensional space-time, point particles can experience a geometric, dimension-specific gravity force, which modifies the usual geodesic equation of motion and provides a link between the cosmological constant and the vacuum θ\theta-angle. The description of such forces fits naturally into a gauge theory of gravity based on the extended Poincar\'e group, {\it i.e.\/} ``string-inspired'' dilaton gravity.Comment: 10 pages, CTP#214

    Extended de Sitter Theory of Two Dimensional Gravitational Forces

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    We present a simple unifying gauge theoretical formulation of gravitational theories in two dimensional spacetime. This formulation includes the effects of a novel matter-gravity coupling which leads to an extended de Sitter symmetry algebra on which the gauge theory is based. Contractions of this theory encompass previously studied cases.Comment: 19pp, no figs., CTP 2228, UCONN-93-

    Energy-Momentum Conservation in General Relativity

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    We discuss general properties of the conservation law associated with a local symmetry. Using Noether's theorem and a generalized Belinfante symmetrization procedure in 3+1 dimensions, a symmetric energy-momentum (pseudo) tensor for the gravitational Einstein-Hilbert action is derived and discussed in detail. In 2+1 dimensions, expressions are obtained for energy and angular momentum arising in the ISO(2,1)ISO(2,1) gauge theoretical formulation of Einstein gravity. In addition, an expression for energy in a gauge theoretical formulation of the string-inspired 1+1 dimensional gravity is derived and compared with the ADM definition of energy.Comment: 18 pages in Plain TeX, MIT-CTP-224

    Quantum States of String-Inspired Lineal Gravity

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    We construct quantum states for a (1+1) dimensional gravity-matter model that is also a gauge theory based on the centrally extended Poincar\'e group. Explicit formulas are found, which exhibit interesting structures. For example wave functionals are gauge invariant except for a gauge non-invariant phase factor that is the Kirillov-Kostant 1-form on the (co-) adjoint orbit of the group. However no evidence for gravity-matter forces is found.Comment: 23 pages in REVTEX, MIT-CTP-227

    A WZW model based on a non-semi-simple group

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    We present a conformal field theory which desribes a homogeneous four dimensional Lorentz-signature space-time. The model is an ungauged WZW model based on a central extension of the Poincar\'e algebra. The central charge of this theory is exactly four, just like four dimensional Minkowski space. The model can be interpreted as a four dimensional monochromatic plane wave. As there are three commuting isometries, other interesting geometries are expected to emerge via O(3,3)O(3,3) duality.Comment: 8 pages, phyzzx, IASSNS-HEP-93/61 Texable versio
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