36,412 research outputs found
Dualisation of the D=7 Heterotic String
The dualisation and the first-order formulation of the D=7 abelian Yang-Mills
supergravity which is the low energy effective limit of the D=7 fully Higssed
heterotic string is discussed. The non-linear coset formulation of the scalars
is enlarged to include the entire bosonic sector by introducing dual fields and
by constructing the Lie superalgebra which generates the dualized coset
element.Comment: 20 page
The One Loop Effective Super-Potential and Non-Holomorphicity
We calculate the Kahlerian and the lowest order non-Kahlerian contributions
to the one loop effective superpotential using super-Feynman graphs in the
massless Wess-Zumino Model, the massive Wess-Zumino Model and N=1, U(1) gauge
theory. We also calculate the Kahlerian term in Yang-Mills Theory for a general
gauge group. Using this latter result we find the one loop Kahlerian
contribution for N=2 Yang-Mills Theory in terms of N=1 superfields and we show
that it can only come from non-holomorphic contributions to the N=2 effective
potential.Comment: LaTeX, 10 pages, 7 figures, uses bezier.sty and ifthen.sty. First
amendment. The results are extended to include the Kahlerian term for a
general renormalisable N=1 supersymmetric theory, containing Wess-Zumino and
Yang-Mills multiplets with a cubic superpotential. One reference has been
changed and one has been added. Second amendment. One acknowledgment has been
altered in the `note added in proof
Representations of G+++ and the role of space-time
We consider the decomposition of the adjoint and fundamental representations
of very extended Kac-Moody algebras G+++ with respect to their regular A type
subalgebra which, in the corresponding non-linear realisation, is associated
with gravity. We find that for many very extended algebras almost all the A
type representations that occur in the decomposition of the fundamental
representations also occur in the adjoint representation of G+++. In
particular, for E8+++, this applies to all its fundamental representations.
However, there are some important examples, such as An+++, where this is not
true and indeed the adjoint representation contains no generator that can be
identified with a space-time translation. We comment on the significance of
these results for how space-time can occur in the non-linear realisation based
on G+++. Finally we show that there is a correspondence between the A
representations that occur in the fundamental representation associated with
the very extended node and the adjoint representation of G+++ which is
consistent with the interpretation of the former as charges associated with
brane solutions.Comment: 45 pages, 9 figures, 9 tables, te
Dualisation of the Salam-Sezgin D=8 Supergravity
The first-order formulation of the Salam-Sezgin D=8 supergravity coupled to N
vector multiplets is discussed. The non-linear realization of the bosonic
sector of the D=8 matter coupled Salam-Sezgin supergravity is introduced by the
dualisation of the fields and by constructing the Lie superalgebra of the
symmetry group of the doubled field strength.Comment: 15 page
Dualisation of the D=9 Matter Coupled Supergravity
We perform the bosonic dualisation of the matter coupled N=1, D=9
supergravity. We derive the Lie superalgebra which parameterizes the coset map
whose Cartan form realizes the second-order bosonic field equations. Following
the non-linear coset construction we present the first-order formulation of the
bosonic field equations as a twisted self-duality condition.Comment: 16 page
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An Evaluation of Non-Stochastic Lattice Structures Fabricated Via Electron Beam Melting
Metal foam structures have many applications and can be used as structural supports, heat
exchangers, shock absorbers, and implant materials. Stochastic metal foams having different cell
sizes and densities have been commercially available for a number of years. This paper addresses
a different type of foams which are known as non-stochastic foams, or lattice structures. These
foams have a well defined repeating unit cell structure rather than the random cell structure in
commercially available stochastic foams. The paper reports on preliminary research on the
fabrication of non-stochastic Ti-6Al-4V alloy foams using the Electron Beam Melting process.
Behavior of the structures in compression, bending, and low cycle repeating load tests are
discussed, and recommendations about cell geometry and processing conditions are made.Mechanical Engineerin
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