5,888 research outputs found
Algebraic Topology of Calabi-Yau Threefolds in Toric Varieties
We compute the integral homology (including torsion), the topological
K-theory, and the Hodge structure on cohomology of Calabi-Yau threefold
hypersurfaces and complete intersections in Gorenstein toric Fano varieties.
The methods are purely topological
Wilson Loops, Bianchi Constraints and Duality in Abelian Lattice Models
We introduce new modified Abelian lattice models, with inhomogeneous local
interactions, in which a sum over topological sectors are included in the
defining partition function. The dual models, on lattices with arbitrary
topology, are constructed and they are found to contain sums over topological
sectors, with modified groups, as in the original model. The role of the sum
over sectors is illuminated by deriving the field-strength formulation of the
models in an explicitly gauge-invariant manner. The field-strengths are found
to satisfy, in addition to the usual local Bianchi constraints, global
constraints. We demonstrate that the sum over sectors removes these global
constraints and consequently softens the quantization condition on the global
charges in the system. Duality is also used to construct mappings between the
order and disorder variables in the theory and its dual. A consequence of the
duality transformation is that correlators which wrap around non-trivial cycles
of the lattice vanish identically. For particular dimensions this mapping
allows an explicit expression for arbitrary correlators to be obtained.Comment: LaTeX 30 pages, 6 figures and 2 tables. References updated and
connection with earlier work clarified, final version to appear in Nucl.
Phys.
A Note on the Equality of Algebraic and Geometric D-Brane Charges in WZW Models
The algebraic definition of charges for symmetry-preserving D-branes in
Wess-Zumino-Witten models is shown to coincide with the geometric definition,
for all simple Lie groups. The charge group for such branes is computed from
the ambiguities inherent in the geometric definition.Comment: 12 pages, fixed typos, added references and a couple of remark
Functorial semi-norms on singular homology and (in)flexible manifolds
A functorial semi-norm on singular homology is a collection of semi-norms on
the singular homology groups of spaces such that continuous maps between spaces
induce norm-decreasing maps in homology. Functorial semi-norms can be used to
give constraints on the possible mapping degrees of maps between oriented
manifolds. In this paper, we use information about the degrees of maps between
manifolds to construct new functorial semi-norms with interesting properties.
In particular, we answer a question of Gromov by providing a functorial
semi-norm that takes finite positive values on homology classes of certain
simply connected spaces. Our construction relies on the existence of simply
connected manifolds that are inflexible in the sense that all their self-maps
have degree -1, 0, or 1. The existence of such manifolds was first established
by Arkowitz and Lupton; we extend their methods to produce a wide variety of
such manifolds.Comment: 37 pages, 1 figure; v2: added some references, corrected some typos;
v3: added observation on multiplicative finite functorial semi-norms; v4:
corrected a mistake in Corollary 3.2 (the main results are not affected); to
appear in AG
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