21 research outputs found
Non-Abelian Black Holes in D=5 Maximal Gauged Supergravity
We investigate static non-abelian black hole solutions of anti-de Sitter
Einstein-Yang-Mills-Dilaton gravity, which is obtained as a consistent
truncation of five-dimensional maximal gauged supergravity. If the dilaton is
(consistently) set to zero, the remaining equations of motion, with a
spherically-symmetric ansatz, may be derived from a superpotential. The
associated first-order equations admit an explicit solution supported by a
non-abelian SU(2) gauge potential, which has a logarithmically growing mass
term. In an extremal limit the horizon geometry becomes AdS. If
the dilaton is also excited, the equations of motion cannot easily be solved
explicitly, but we obtain the asymptotic form of the more general non-abelian
black holes in this case. An alternative consistent truncation, in which the
Yang-Mills fields are set to zero, also admits a description in terms of a
superpotential. This allows us to construct explicit wormhole solutions
(neutral spherically-symmetric domain walls). These solutions may be
generalised to dimensions other than five.Comment: Author's address, and a reference, adde
Domain Walls and Massive Gauged Supergravity Potentials
We point out that massive gauged supergravity potentials, for example those
arising due to the massive breathing mode of sphere reductions in M-theory or
string theory, allow for supersymmetric (static) domain wall solutions which
are a hybrid of a Randall-Sundrum domain wall on one side, and a dilatonic
domain wall with a run-away dilaton on the other side. On the anti-de Sitter
(AdS) side, these walls have a repulsive gravity with an asymptotic region
corresponding to the Cauchy horizon, while on the other side the runaway
dilaton approaches the weak coupling regime and a non-singular attractive
gravity, with the asymptotic region corresponding to the boundary of spacetime.
We contrast these results with the situation for gauged supergravity potentials
for massless scalar modes, whose supersymmetric AdS extrema are generically
maxima, and there the asymptotic regime transverse to the wall corresponds to
the boundary of the AdS spacetime. We also comment on the possibility that the
massive breathing mode may, in the case of fundamental domain-wall sources,
stabilize such walls via a Goldberger-Wise mechanism.Comment: latex file, 11 pages, 3 figure
Decoupling Limit, Lens Spaces and Taub-NUT: D=4 Black Hole Microscopics from D=5 Black Holes
We study the space-times of non-extremal intersecting p-brane configurations
in M-theory, where one of the components in the intersection is a ``NUT,'' i.e.
a configuration of the Taub-NUT type. Such a Taub-NUT configuration
corresponds, upon compactification to D=4, to a Gross-Perry-Sorkin (GPS)
monopole. We show that in the decoupling limit of the CFT/AdS correspondence,
the 4-dimensional transverse space of the NUT configuration in D=5 is foliated
by surfaces that are cyclic lens spaces S^3/Z_N, where N is the quantised
monopole charge. By contrast, in D=4 the 3-dimensional transverse space of the
GPS monopole is foliated by 2-spheres. This observation provides a
straightforward interpretation of the microscopics of a D=4 string-theory black
hole, with a GPS monopole as one of its constituents, in terms of the
corresponding D=5 black hole with no monopole. Using the fact that the
near-horizon region of the NUT solution is a lens space, we show that if the
effect of the Kaluza-Klein massive modes is neglected, p-brane configurations
can be obtained from flat space-time by means of a sequence of dimensional
reductions and oxidations, and U-duality transformations.Comment: 22 pages, Late
Consistent Kaluza-Klein Sphere Reductions
We study the circumstances under which a Kaluza-Klein reduction on an
n-sphere, with a massless truncation that includes all the Yang-Mills fields of
SO(n+1), can be consistent at the full non-linear level. We take as the
starting point a theory comprising a p-form field strength and (possibly) a
dilaton, coupled to gravity in the higher dimension D. We show that aside from
the previously-studied cases with (D,p)=(11,4) and (10,5) (associated with the
S^4 and S^7 reductions of D=11 supergravity, and the S^5 reduction of type IIB
supergravity), the only other possibilities that allow consistent reductions
are for p=2, reduced on S^2, and for p=3, reduced on S^3 or S^{D-3}. We
construct the fully non-linear Kaluza-Klein Ansatze in all these cases. In
particular, we obtain D=3, N=8, SO(8) and D=7, N=2, SO(4) gauged supergravities
from S^7 and S^3 reductions of N=1 supergravity in D=10.Comment: 27 pages, Latex, typo correcte
Entropy-Product Rules for Charged Rotating Black Holes
We study the universal nature of the product of the entropies of all horizons
of charged rotating black holes. We argue, by examining further explicit
examples, that when the maximum number of rotations and/or charges are turned
on, the entropy product is expressed in terms of angular momentum and/or
charges only, which are quantized. (In the case of gauged supergravities, the
entropy product depends on the gauge-coupling constant also.) In two-derivative
gravities, the notion of the "maximum number" of charges can be defined as
being sufficiently many non-zero charges that the Reissner-Nordstrom black hole
arises under an appropriate specialisation of the charges. (The definition can
be relaxed somewhat in charged AdS black holes in .) In
higher-derivative gravity, we use the charged rotating black hole in
Weyl-Maxwell gravity as an example for which the entropy product is still
quantized, but it is expressed in terms of the angular momentum only, with no
dependence on the charge. This suggests that the notion of maximum charges in
higher-derivative gravities requires further understanding.Comment: References added. 24 page
Domain Walls with Localised Gravity and Domain-Wall/QFT Correspondence
We review general domain-wall solutions supported by a delta-function source,
together with a single pure exponential scalar potential in supergravity. These
scalar potentials arise from a sphere reduction in M-theory or string theory.
There are several examples of flat (BPS) domain walls that lead to a
localisation of gravity on the brane, and for these we obtain the form of the
corrections to Newtonian gravity. These solutions are lifted back on certain
internal spheres to D=11 and D=10 as M-branes and D-branes. We find that the
domain walls that can trap gravity yield M-branes or Dp-branes that have a
natural decoupling limit, i.e. p\le 5, with the delta-function source providing
an ultra-violet cut-off in a dual quantum field theory. This suggests that the
localisation of gravity can generally be realised within a Domain-wall/QFT
correspondence, with the delta-function domain-wall source providing a cut-off
from the space-time boundary for these domain-wall solutions. We also discuss
the form of the one-loop corrections to the graviton propagator from the
boundary QFT that would reproduce the corrections to the Newtonian gravity on
the domain wall.Comment: plain latex, 25 pages, typos correcte
Closed-form Absorption Probability of Certain D=5 and D=4 Black Holes and Leading-Order Cross-Section of Generic Extremal p-branes
We obtain the closed-form absorption probabilities for minimally-coupled
massless scalars propagating in the background of D=5 single-charge and D=4
two-charge black holes. These are the only two examples of extremal black holes
with non-vanishing absorption probabilities that can be solved in closed form
for arbitrary incident frequencies. In both cases, the absorption probability
vanishes when the frequency is below a certain threshold, and we discuss the
connection between this phenomenon and the behaviour of geodesics in these
black hole backgrounds. We also obtain leading-order absorption cross-sections
for generic extremal p-branes, and show that the expression for the
cross-section as a function of frequency coincides with the leading-order
dependence of the entropy on the temperature in the corresponding near-extremal
p-branes.Comment: Latex (3 times), 20 page
M-theory PP-waves, Penrose Limits and Supernumerary Supersymmetries
We study supersymmetric pp-waves in M-theory, their dimensional reduction to
D0-branes or pp-waves in type IIA, and their T-dualisation to solutions in the
type IIB theory. The general class of pp-waves that we consider encompass the
Penrose limits of AdS_p\times S^q with (p,q)=(4,7), (7,4), (3,3), (3,2), (2,3),
(2,2), but includes also many other examples that can again lead to
exactly-solvable massive strings, but which do not arise from Penrose limits.
All the pp-waves in D=11 have 16 ``standard'' Killing spinors, but in certain
cases one finds additional, or ``supernumerary,'' Killing spinors too. These
give rise to linearly-realised supersymmetries in the string or matrix models.
A focus of our investigation is on the circumstances when the Killing spinors
are independent of particular coordinates (x^+ or transverse-space
coordinates), since these will survive at the field-theory level in dimensional
reduction or T-dualisation.Comment: Latex, 23 pages. Reference added, minor corrections made, and various
notational and convention changes in Green-Schwarz actions, following
associated improvements in hep-th/990720