13,501 research outputs found
New Gauged N=8, D=4 Supergravities
New gaugings of four dimensional N=8 supergravity are constructed, including
one which has a Minkowski space vacuum that preserves N=2 supersymmetry and in
which the gauge group is broken to . Previous gaugings used the
form of the ungauged action which is invariant under a rigid symmetry
and promoted a 28-dimensional subgroup ( or the
non-semi-simple contraction ) to a local gauge group. Here, a
dual form of the ungauged action is used which is invariant under
instead of and new theories are obtained by gauging 28-dimensional
subgroups of . The gauge groups are non-semi-simple and are different
real forms of the groups, denoted , and the new
theories have a rigid SU(2) symmetry. The five dimensional gauged N=8
supergravities are dimensionally reduced to D=4. The gauge
theories reduce, after a duality transformation, to the
gauging while the gauge theory reduces to the gauge
theory. The new theories are related to the old ones via an analytic
continuation. The non-semi-simple gaugings can be dualised to forms with
different gauge groups.Comment: 33 pages. Reference adde
De Sitter Space in Supergravity and M Theory
Two ways in which de Sitter space can arise in supergravity theories are
discussed. In the first, it arises as a solution of a conventional
supergravity, in which case it necessarily has no Killing spinors. For example,
de Sitter space can arise as a solution of N=8 gauged supergravities in four or
five dimensions. These lift to solutions of 11-dimensional supergravity or D=10
IIB supergravity which are warped products of de Sitter space and non-compact
spaces of negative curvature. In the second way, de Sitter space can arise as a
supersymmetric solution of an unconventional supergravity theory, which
typically has some kinetic terms with the `wrong' sign; such solutions are
invariant under a de Sitter supergroup. Such solutions lift to supersymmetric
solutions of unconventional supergravities in D=10 or D=11, which nonetheless
arise as field theory limits of theories that can be obtained from M-theory by
timelike T-dualities and related dualities. Brane solutions interpolate between
these solutions and flat space and lead to a holographic duality between
theories in de Sitter vacua and Euclidean conformal field theories. Previous
results are reviewed and generalised, and discussion is included of
Kaluza-Klein theory with non-compact internal spaces, brane and cosmological
solutions, and holography on de Sitter spaces and product spaces.Comment: Referneces added, 36 page
Gauged Heterotic Sigma-Models
The gauging of isometries in general sigma-models which include fermionic
terms which represent the interaction of strings with background Yang-Mills
fields is considered. Gauging is possible only if certain obstructions are
absent. The quantum gauge anomaly is discussed, and the (1,0) supersymmetric
generalisation of the gauged action given.Comment: 10 pages, phyzzx, QMW-93-25 (Blank lines created by mailer removed,
so this version should be TeXable
U-Duality and BPS Spectrum of Super Yang-Mills Theory and M-Theory
It is shown that the BPS spectrum of Super-Yang-Mills theory on , which fits into representations of the U-duality group for M-theory
compactified on , in accordance with the matrix-theory conjecture, in
fact fits into representations of the U-duality group for M-theory on
, the extra dualities realised as generalised Nahm transformations.
The spectrum of BPS M-branes is analysed, new branes are discussed and matrix
theory applications described.Comment: 18 Pages, Tex, Phyzzx Macro. References added, minor correction
Matrix Theory, U-Duality and Toroidal Compactifications of M-Theory
Using U-duality, the properties of the matrix theories corresponding to the
compactification of M-theory on are investigated. The couplings of the
dimensional effective Super-Yang-Mills theory to all the M-theory moduli
is deduced and the spectrum of BPS branes in the SYM gives the corresponding
spectrum of the matrix theory.Known results are recovered for and
predictions for are proposed. For , the spectrum includes
branes arising from YM instantons, and U-duality interchanges momentum modes
with brane wrapping modes.For , there is a generalised -angle which
couples to instantonic 3-branes and which combines with the SYM coupling
constant to take values in , acted on by an subgroup
of the U-duality group . For , there is an
symmetry, suggesting that the matrix theory could be a scale-invariant
dimensional theory on in these cases, as is already known
to be the case for ; evidence is found suggesting this happens for
but not .Comment: 28 Pages, Phyzzx Macro. Minor correction
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