342 research outputs found
On the stability and spectrum of non-supersymmetric AdS(5) solutions of M-theory compactified on Kahler-Einstein spaces
Eleven-dimensional supergravity admits non-supersymmetric solutions of the
form AdS(5)xM(6) where M(6) is a positive Kahler-Einstein space. We show that
the necessary and sufficient condition for such solutions to be stable against
linearized bosonic supergravity perturbations can be expressed as a condition
on the spectrum of the Laplacian acting on (1,1)-forms on M(6). For M(6)=CP(3),
this condition is satisfied, although there are scalars saturating the
Breitenlohner-Freedman bound. If M(6) is a product S(2)xM(4) (where M(4) is
Kahler-Einstein) then there is an instability if M(4) has a continuous
isometry. We show that a potential non-perturbative instability due to 5-brane
nucleation does not occur. The bosonic Kaluza-Klein spectrum is determined in
terms of eigenvalues of operators on M(6).Comment: 21 pages. v2: Includes SU(4) quantum numbers for CP3 case, typos
fixed, refs adde
Spectrum of Higher Derivative 6D Chiral Supergravity
Gauged off-shell Maxwell-Einstein supergravity in six dimensions with N=(1,0)
supersymmetry has a higher derivative extension afforded by a supersymmetrized
Riemann squared term. This theory admits a supersymmetric Minkowski x S^2
compactification with a U(1) monopole of unit charge on S^2. We determine the
full spectrum of the theory on this background. We also determine the spectrum
on a non-supersymmetric version of this compactification in which the monopole
charge is different from unity, and we find the peculiar feature that there are
massless gravitini in a representation of the S^2 isometry group determined by
the monopole charge.Comment: typos correcte
Properties of some conformal field theories with M-theory duals
By studying classes of supersymmetric solutions of D=11 supergravity with
AdS_5 factors, we determine some properties of the dual four-dimensional N=1
superconformal field theories. For some explicit solutions we calculate the
central charges and also the conformal dimensions of certain chiral primary
operators arising from wrapped membranes. For the most general class of
solutions we show that there is a consistent Kaluza-Klein truncation to minimal
D=5 gauged supergravity. This latter result allows us to study some aspects of
the dual strongly coupled thermal plasma with a non-zero R-charge chemical
potential and, in particular, we show that the ratio of the shear viscosity to
the entropy density has the universal value of 1/4 pi.Comment: Consistent truncation extended to include fermions. Reference added.
28 page
Consistent Group and Coset Reductions of the Bosonic String
Dimensional reductions of pure Einstein gravity on cosets other than tori are
inconsistent. The inclusion of specific additional scalar and p-form matter can
change the situation. For example, a D-dimensional Einstein-Maxwell-dilaton
system, with a specific dilaton coupling, is known to admit a consistent
reduction on S^2= SU(2)/U(1), of a sort first envisaged by Pauli. We provide a
new understanding, by showing how an S^3=SU(2) group-manifold reduction of
(D+1)-dimensional Einstein gravity, of a type first indicated by DeWitt, can be
broken into in two steps; a Kaluza-type reduction on U(1) followed by a
Pauli-type coset reduction on S^2. More generally, we show that any
D-dimensional theory that itself arises as a Kaluza U(1) reduction from (D+1)
dimensions admits a consistent Pauli reduction on any coset of the form G/U(1).
Extensions to the case G/H are given. Pauli coset reductions of the bosonic
string on G= (G\times G)/G are believed to be consistent, and a consistency
proof exists for S^3=SO(4)/SO(3). We examine these reductions, and arguments
for consistency, in detail. The structures of the theories obtained instead by
DeWitt-type group-manifold reductions of the bosonic string are also studied,
allowing us to make contact with previous such work in which only singlet
scalars are retained. Consistent truncations with two singlet scalars are
possible. Intriguingly, despite the fact that these are not supersymmetric
models, if the group manifold has dimension 3 or 25 they admit a superpotential
formulation, and hence first-order equations yielding domain-wall solutions.Comment: Latex, 5 figures, 45 pages, minor correction
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