169 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
Brane mapping under
We present the evidence that is a nonperturbative symmetry of
Type II string theory. We argue that is a symmetry of string
theory as much as the of the Type II string is and how the branes
are mapped under the modding. NS branes are mapped into the NS
branes with the same world volume dimensions but with the different chiral
structure. Supersymmetric Dp-branes (bound with anti-Dp branes) are mapped to
unstable nonsupersymmetric Dp-branes, which has D(p-1)-branes as kink solutions
according to Horava.Comment: 6 pages, interpretation of the boundary state mapping in terms of
D-branes is clarified and a reference adde
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
A Note on the Stringy Embeddings of Certain N = 2 Dualities
Seiberg-Witten theory can be embedded in F-theory using D3 branes probing an
orientifold geometry. The non-perturbative corrections in the orientifold
picture map directly to the instanton corrections in the corresponding gauge
theory that convert the classical moduli space to the quantum one. In this
short review we argue that the recently proposed class of conformal Gaiotto
models may also be embedded in F-theory. The F-theory constructions help us not
only to understand the Gaiotto dualities but also to extend to the
non-conformal cases with and without cascading behaviors. For the conformal
cases, the near horizon geometries in F-theory capture both the UV and IR
behaviors succinctly.Comment: 6 pages, LaTeX, Based on the talk given by K. D at the Theory Canada
Conference June 2012; v2: Typos corrected and references adde
Noncommutative Tachyons
When unstable Dp-branes in type II string theory are placed in a B-field, the
resulting tachyonic world-volume theory becomes noncommutative. We argue that
for large noncommutativity parameter, condensation of the tachyon as a
noncommutative soliton leads to new decay modes of the Dp-brane into
(p-2)-brane configurations, which we interpret as suitably smeared BPS
D(p-1)-branes. Some of these configurations are metastable. We discuss various
generalizations of this decay process.Comment: 15 pages, harvmac (b
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