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 $SU(3)xU(1)^2$. Previous gaugings used the
form of the ungauged action which is invariant under a rigid $SL(8,R)$ symmetry
and promoted a 28-dimensional subgroup ($SO(8),SO(p,8-p)$ or the
non-semi-simple contraction $CSO(p,q,8-p-q)$) to a local gauge group. Here, a
dual form of the ungauged action is used which is invariant under $SU^*(8)$
instead of $SL(8,R)$ and new theories are obtained by gauging 28-dimensional
subgroups of $SU^*(8)$. The gauge groups are non-semi-simple and are different
real forms of the $CSO(2p,8-2p)$ groups, denoted $CSO^*(2p,8-2p)$, and the new
theories have a rigid SU(2) symmetry. The five dimensional gauged N=8
supergravities are dimensionally reduced to D=4. The $D=5,SO(p,6-p)$ gauge
theories reduce, after a duality transformation, to the $D=4,CSO(p,6-p,2)$
gauging while the $SO^*(6)$ gauge theory reduces to the $D=4, CSO^*(6,2)$ 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 $T^d\times
\R$, which fits into representations of the U-duality group for M-theory
compactified on $T^{d}$, in accordance with the matrix-theory conjecture, in
fact fits into representations of the U-duality group for M-theory on
$T^{d+1}$, 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 $T^d$ are investigated. The couplings of the
$d+1$ 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 $d\le 5$ and
predictions for $d>5$ are proposed. For $d>3$, the spectrum includes $d-4$
branes arising from YM instantons, and U-duality interchanges momentum modes
with brane wrapping modes.For $d=6$, there is a generalised $\th$-angle which
couples to instantonic 3-branes and which combines with the SYM coupling
constant to take values in $SL(2,\R)/U(1)$, acted on by an $SL(2,\Z)$ subgroup
of the U-duality group $E_6(\Z)$. For $d=4,7,8$, there is an $SL(d+1)$
symmetry, suggesting that the matrix theory could be a scale-invariant $d+2$
dimensional theory on $T^{d+1} \times \R$ in these cases, as is already known
to be the case for $d=4$; evidence is found suggesting this happens for $d=8$
but not $d=7$.Comment: 28 Pages, Phyzzx Macro. Minor correction

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