42 research outputs found
A Superconnection for Riemannian Gravity as Spontaneously Broken SL(4,R) Gauge Theory
A superconnection is a supermatrix whose even part contains the
gauge-potential one-forms of a local gauge group, while the odd parts contain
the (0-form) Higgs fields; the combined grading is thus odd everywhere. We
demonstrate that the simple supergroup (rank=3) in Kac'
classification (even subgroup ) prverline {SL}(4,R)\bar{SL}(4,R)\bar{SO}(1,3)$ unbroken. As a result, post-Riemannian SKY
gravity yields Einstein's theory as a low-energy (longer range) effective
theory. The theory is renormalizable and may be unitary.Comment: 11 pages, late
Improved Energy-Momentum Currents in Metric-Affine Spacetime
In Minkowski spacetime it is well-known that the canonical energy-momentum
current is involved in the construction of the globally conserved currents of
energy-momentum and total angular momentum. For the construction of conserved
currents corresponding to (approximate) scale and proper conformal symmetries,
however, an improved energy-momentum current is needed. By extending the
Minkowskian framework to a genuine metric-affine spacetime, we find that the
affine Noether identities and the conformal Killing equations enforce this
improvement in a rather natural way. So far, no gravitational dynamics is
involved in our construction. The resulting dilation and proper conformal
currents are conserved provided the trace of the energy-momentum current
satisfies a (mild) scaling relation or even vanishes.Comment: 14p
World Spinors - Construction and Some Applications
The existence of a topological double-covering for the and
diffeomorphism groups is reviewed. These groups do not have finite-dimensional
faithful representations. An explicit construction and the classification of
all , unitary irreducible representations is presented.
Infinite-component spinorial and tensorial fields,
"manifields", are introduced. Particle content of the ladder manifields, as
given by the "little" group is determined. The manifields are
lifted to the corresponding world spinorial and tensorial manifields by making
use of generalized infinite-component frame fields. World manifields transform
w.r.t. corresponding representations, that are constructed
explicitly.Comment: 19 pages, Te
Cosmological Surrealism: More than ``Eternal Reality" is Needed
Inflationary Cosmology makes the universe ``eternal" and provides for
recurrent universe creation, ad infinitum -- making it also plausible to assume
that ``our" Big Bang was also preceeded by others, etc.. However, GR tells us
that in the ``parent" universe's reference frame, the newborn universe's
expansion will never start. Our picture of ``reality" in spacetime has to be
enlarged.Comment: 7 pages, TAUP N23
The strongest force
This article by one of the co-discoverers of 'the eightfold way' of classifying strongly interacting particles, first appeared in 'Science Year 1968' and is reproduced here by kind permission of the publishers