157 research outputs found
Anomaly Inflow on Orientifold Planes
We examine some six-dimensional orientifold models with
supersymmetry, which can be realised as intersecting 7-branes and 7-planes.
These models are studied in the light of recent work showing that orientifold
planes carry anomalous gravitational couplings on their world-volume. We show
that gravitational anomalies can be locally cancelled by these new couplings at
every point in the internal space, under the assumption that the anomaly
residing on orientifold planes is distributed in a particular way among
brane-plane and plane-plane intersections.Comment: harvmac, 12 pages (b); Some changes in wording, in order to convey
more accurately what is being done; no changes in computations or formula
BPS Nature of 3-String Junctions
We study BPS-saturated classical solutions for the world-sheet theory of a
D-string in the presence of a point charge. These solutions are interpreted as
describing planar 3-string junctions, which arise because the original D-string
is deformed by the presence of the inserted charge. We compute the angles of
the junctions and show that the vector sum of string tensions is zero,
confirming a conjecture of Schwarz that such configurations are BPS states.Comment: 7 pages, harvmac (b), 3 figure
Constraints on "rare" dyon decays
We obtain the complete set of constraints on the moduli of N=4 superstring
compactifications that permit "rare" marginal decays of 1/4-BPS dyons to take
place. The constraints are analysed in some special cases. The analysis extends
in a straightforward way to multi-particle decays. We discuss the possible
relation between general multi-particle decays and multi-centred black holes.Comment: 27 page
Brane Constructions, Fractional Branes and Anti-deSitter Domain Walls
Compactifications of type IIB string theory on AdS5 x X5, where X5 is an
Einstein space, can have one-fourth or half maximal supersymmetry for certain
choices of X5. Some of these theories admit exotic domain walls arising from
5-branes wrapping 2-cycles in X5. We explore the relationship among these
domain walls, fractional branes and branes stretched on intervals. World-volume
fluxes in the wrapped branes play an important role in the analysis. We draw
some parallels between the AdS background with exotic domain walls and N=1
supersymmetric MQCD, and identify other extended objects on the AdS side in the
dual brane construction. The process of brane creation is used to give an
alternate derivation of the relationship between fractional branes and branes
on intervals.Comment: harvmac, 34 pages (b), 8 figures; Reference adde
Killing Spinors and Supersymmetric AdS Orbifolds
We examine the behaviour of Killing spinors on AdS5 under various discrete
symmetries of the spacetime. In this way we discover a number of supersymmetric
orbifolds, reproducing the known ones and adding a few novel ones to the list.
These orbifolds break the SO(4,2) invariance of AdS5 down to subgroups. We also
make some comments on the non-compact Stiefel manifold W{4,2}.Comment: 16 pages, harvmac (b
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