2,350 research outputs found
A Vertex Formalism for Local Ruled Surfaces
We develop a vertex formalism for topological string amplitudes on ruled
surfaces with an arbitrary number of reducible fibers embedded in a Calabi-Yau
threefold. Our construction is based on large N duality and localization with
respect to a degenerate torus action. We also discuss potential generalizations
of our formalism to a broader class of Calabi-Yau threefolds using the same
underlying principles.Comment: 24 pages, 12 figures; v2: minor changes; v3: explanations added,
results unchange
Neveu-Schwarz Five-Branes And Matrix String Theory On K3
The Matrix theory description of Type IIA string theory on a compact K3
surface as the theory of Neveu-Schwarz five-branes on is
analyzed. The full multiplet of space-time BPS states is identified in the
five-brane world-volume as fluxes.Comment: harvmac, 12 pages, some changes in the T-duality on K3 sectio
Spectral Covers, Charged Matter and Bundle Cohomology
We consider four dimensional heterotic compactifications on smooth elliptic
Calabi-Yau threefolds. Using spectral cover techniques, we study bundle
cohomology groups corresponding to charged matter multiplets. The analysis
shows that in generic situations, the resulting charged matter spectrum is
stable under deformations of the vector bundle.Comment: 17 pages, harvmac; minor change
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