921 research outputs found
Dyonic Membranes
We present dyonic multi-membrane solutions of the N=2 D=8 supergravity theory
that serves as the effective field theory of the -compactified type II
superstring theory. The `electric' charge is fractional for generic asymptotic
values of an axion field, as for D=4 dyons. These membrane solutions are
supersymmetric, saturate a Bogomolnyi bound, fill out orbits of an
subgroup of the type II D=8 T-duality group, and are non-singular when
considered as solutions of -compactified D=11 supergravity. On
compactification to D=4, the conjectured type II/heterotic equivalence allows
the group to be reinterpreted as the S-duality group of the
toroidally compactified heterotic string and the dyonic membranes wrapped
around homology two-cycles of as S-duals of perturbative heterotic string
states.Comment: Phyzzx. 27 pp. Additional para. added to introductio
Super p-branes
It is shown that the extension of the spacetime supersymmetric Green-
Schwarz covariant superstring action to p-dimensional extended objects (p-branes) is possible if and only if the on-shell p-dimensional bose and fermi
degrees of freedom are equal. This is further evidence for world-tube supersymmetry
in these models. All the p-brane models are related to superstring
actions in d = 3, 4, 6 or 10 dimensions by double dimensional reduction, (which
we generalise to reduction on arbitrary compact spaces), and we also show how
they may be considered as topological defects of supergravity theories
Brane Dynamics From the Born-Infeld Action
We use the abelian Born-Infeld action for the worldvolume gauge field and
transverse displacement scalars to explore new aspects of D-brane structure and
dynamics. We study several classic gauge field configurations, including point
charges in any worldvolume dimension and vortices in two worldvolume
dimensions, and show that, with an appropriate excitation of the transverse
coordinate field, they are BPS-saturated solutions. The Coulomb point charge
solutions turn out to represent, with considerable fidelity, fundamental
strings attached to the brane (their magnetic counterparts describe D1-branes
attached to D3-branes). We also show that S-matrix for small excitations
propagating on the point charge solution is consistent with (and gives further
illuminating information about) Polchinski's effective open string boundary
condition.Comment: 16 pages, 3 figures. Minor typos fixe
A new maximally supersymmetric background of IIB superstring theory
We present a maximally supersymmetric IIB string background. The geometry is
that of a conformally flat lorentzian symmetric space G/K with solvable G, with
a homogeneous five-form flux. We give the explicit supergravity solution,
compute the isometries, the 32 Killing spinors, and the symmetry superalgebra,
and then discuss T-duality and the relation to M-theory.Comment: 17 page
The `s-rule' exclusion principle and vacuum interpolation in worldvolume dynamics
We show how the worldvolume realization of the Hanany-Witten effect for a
supersymmetric D5-brane in a D3 background also provides a classical
realization of the `s-rule' exclusion principle. Despite the supersymmetry, the
force on the D5-brane vanishes only in the D5 `ground state', which is shown to
interpolate between 6-dimensional Minkowski space and an -invariant
geometry. The M-theory analogue of these results is briefly
discussed.Comment: 25 pages, 9 figures, LaTeX JHEP styl
Entanglement Interpretation of Black Hole Entropy in String Theory
We show that the entropy resulting from the counting of microstates of non
extremal black holes using field theory duals of string theories can be
interpreted as arising from entanglement. The conditions for making such an
interpretation consistent are discussed. First, we interpret the entropy (and
thermodynamics) of spacetimes with non degenerate, bifurcating Killing horizons
as arising from entanglement. We use a path integral method to define the
Hartle-Hawking vacuum state in such spacetimes and discuss explicitly its
entangled nature and its relation to the geometry. If string theory on such
spacetimes has a field theory dual, then, in the low-energy, weak coupling
limit, the field theory state that is dual to the Hartle-Hawking state is a
thermofield double state. This allows the comparison of the entanglement
entropy with the entropy of the field theory dual, and thus, with the
Bekenstein-Hawking entropy of the black hole. As an example, we discuss in
detail the case of the five dimensional anti-de Sitter, black hole spacetime
A Note on Acceleration from Product Space Compactification
We study compactifications of Einstein gravity on product spaces in vacuum
and their acceleration phases. Scalar potentials for the dimensionally reduced
effective theory are found to be of exponential form and exact solutions are
obtained for a class of product spaces. The inflation in our solutions is not
sufficient for the early universe. We comment on the possibility of obtaining
sufficient inflation by compactification in general.Comment: 19 pages, 6 figures, v2: further comments and references added, v3:
typos fixe
The holonomy of the supercovariant connection and Killing spinors
We show that the holonomy of the supercovariant connection for M-theory
backgrounds with Killing spinors reduces to a subgroup of SL(32-N,\bR)\st
(\oplus^N \bR^{32-N}). We use this to give the necessary and sufficient
conditions for a background to admit Killing spinors. We show that there is
no topological obstruction for the existence of up to 22 Killing spinors in
eleven-dimensional spacetime. We investigate the symmetry superalgebras of
supersymmetric backgrounds and find that their structure constants are
determined by an antisymmetric matrix. The Lie subalgebra of bosonic generators
is related to a real form of a symplectic group. We show that there is a
one-one correspondence between certain bases of the Cartan subalgebra of
sl(32, \bR) and supersymmetric planar probe M-brane configurations. A
supersymmetric probe configuration can involve up to 31 linearly independent
planar branes and preserves one supersymmetry. The space of supersymmetric
planar probe M-brane configurations is preserved by an SO(32,\bR) subgroup of
SL(32, \bR).Comment: 27 pages, a key reference was added. v3: minor change
A Brane Teaser
In this note we study the puzzle posed by two M5-branes intersecting on a
string (or equivalently, a single M5-brane wrapping a holomorphic four-cycle in
C^4). It has been known for a while that this system is different from all
other configurations built using self-intersecting M-branes; in particular the
corresponding supergravity solution exhibits various curious features which
have remained unexplained. We propose that the resolution to these puzzles lies
in the existence of a non-zero two-form on the M5-brane world-volume.Comment: 21 pages. References adde
Lodged in the throat: Internal infinities and AdS/CFT
In the context of AdS3/CFT2, we address spacetimes with a certain sort of
internal infinity as typified by the extreme BTZ black hole. The internal
infinity is a null circle lying at the end of the black hole's infinite throat.
We argue that such spacetimes may be described by a product CFT of the form
CFT-L * CFT-R, where CFT-R is associated with the asymptotically AdS boundary
while CFT-L is associated with the null circle. Our particular calculations
analyze the CFT dual of the extreme BTZ black hole in a linear toy model of
AdS3/CFT2. Since the BTZ black hole is a quotient of AdS3, the dual CFT state
is a corresponding quotient of the CFT vacuum state. This state turns out to
live in the aforementioned product CFT. We discuss this result in the context
of general issues of AdS/CFT duality and entanglement entropy.Comment: 11 pages, 2 figures; v2 - some typos corrected, minor revision
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