790 research outputs found
Dynamically broken Anti-de Sitter action for gravity
Due to a suitable Higgs mechanism, a standard Anti-de Sitter gauge theory
becomes spontaneously broken. The resulting Lorentz invariant gravitational
action includes the Hilbert-Einstein term of ordinary Einstein-Cartan gravity
with cosmological constant, plus contributions quadratic in curvature and
torsion, and a scalar Higgs sector.Comment: 7 Revtex pages, no figure
Motion in gauge theories of gravity
A description of motion is proposed, adapted to the composite bundle
interpretation of Poincar\'e Gauge Theory. Reference frames, relative positions
and time evolution are characterized in gauge-theoretical terms. The approach
is illustrated by an appropriate formulation of the familiar example of orbital
motion induced by Schwarzschild spacetime.Comment: 24 pages, 6 figures, revised version with minor change
An exact solution of the metric-affine gauge theory with dilation, shear, and spin charges
The spacetime of the metric-affine gauge theory of gravity (MAG) encompasses
{\it nonmetricity} and {\it torsion} as post-Riemannian structures. The sources
of MAG are the conserved currents of energy-momentum and dilation, shear and
spin. We present an exact static spherically symmetric vacuum solution of the
theory describing the exterior of a lump of matter carrying mass and dilation,
shear and spin charges.Comment: 13 pages, RevTe
A cosmological model in Weyl-Cartan spacetime
We present a cosmological model for early stages of the universe on the basis
of a Weyl-Cartan spacetime. In this model, torsion and
nonmetricity are proportional to the vacuum polarization.
Extending earlier work of one of us (RT), we discuss the behavior of the cosmic
scale factor and the Weyl 1-form in detail. We show how our model fits into the
more general framework of metric-affine gravity (MAG).Comment: 19 pages, 5 figures, typos corrected, uses IOP style fil
Gravitational contribution to fermion masses
In the context of a nonlinear gauge theory of the Poincar\'e group, we show
that covariant derivatives of Dirac fields include a coupling to the
translational connections, manifesting itself in the matter action as a
universal background mass contribution to fermions.Comment: revtex4, 9 pages, no figures, to be published in Eur.Phys.J.C, 200
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