4,782 research outputs found
Anti-de Sitter branes with Neveu-Schwarz and Ramond-Ramond backgrounds
We review some facts about AdS2xS2 branes in AdS3xS3 with a Neveu-Schwarz
background, and consider the case of Ramond-Ramond backgrounds. We compute the
spectrum of quadratic fluctuations in the low-energy approximation and discuss
the open-string geometry.Comment: 8 pages, uses JHEP3.cl
A worldsheet extension of O(d,d;Z)
We study superconformal interfaces between N=(1,1) supersymmetric sigma
models on tori, which preserve a u(1)^{2d} current algebra. Their fusion is
non-singular and, using parallel transport on CFT deformation space, it can be
reduced to fusion of defect lines in a single torus model. We show that the
latter is described by a semi-group extension of O(d,d;Q), and that (on the
level of Ramond charges) fusion of interfaces agrees with composition of
associated geometric integral transformations. This generalizes the well-known
fact that T-duality can be geometrically represented by Fourier-Mukai
transformations. Interestingly, we find that the topological interfaces between
torus models form the same semi-group upon fusion. We argue that this
semi-group of orbifold equivalences can be regarded as the \alpha' deformation
of the continuous O(d,d) symmetry of classical supergravity.Comment: 71 pages, 1 figure, minor additions and correction
(Half) a Lecture on D-branes
This is a concise foreword to, rather than a review of D-brane physics.Comment: 20 pages, Latex. To appear in Proceedings of the Workshop on Gauge
Theories, Applied Supersymmetry and Quantum Gravity (Imperial College,
London, July 1996). Two misprints in eqs. (3.24) and (3.25) correcte
Microstates and near-horizon D-brane probes
In hep-th/0412322, Gaiotto, Strominger and Yin proposed a novel way of
counting black hole microstates by counting the quantum mechanical ground
states of probe branes placed in the near-horizon black hole background. We
discuss the generalization of this proposal to the case of two-charge D0-D4
`small' black holes in type IIA. We also describe the construction of BPS
D-brane probes in the near-horizon region of the 2-charge D1-D5 system in type
IIB. Based on hep-th/0505176, hep-th/0607150.Comment: 5 pages, contribution to the proceedings of the RTN project
`Constituents, Fundamental Forces and Symmetries of the Universe' conference
in Napoli, October 9 - 13, 200
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