1,651 research outputs found
K-theory and Ramond-Ramond charge
We discuss the relation between the Ramond-Ramond charges of D-branes and the
topology of Chan-Paton vector bundles. We show that a topologically nontrivial
normal bundle induces RR charge and that the result fits in perfectly with the
proposal that D-brane charge is the topology of the Chan-Paton bundle, regarded
as an element of K-theory.Comment: 8 pages, harvmac. Partial retraction of the partial retraction, as
explained in note adde
Mirror symmetry & supersymmetry on SU(4)-structure backgrounds
We revisit the backgrounds of type IIB on manifolds with -structure
and discuss two sets of solutions arising from internal geometries that are
complex and symplectic respectively. Both can be realized in terms of
generalized complex geometry. We identify a map which relates the complex and
symplectic supersymmetric systems. In the semi-flat torus bundle setting this
map corresponds to T-duality and suggest a way of extending the mirror
transform to non-K\"ahler geometries.Comment: 40 page
N=2 higher-derivative couplings from strings
We consider the Calabi-Yau reduction of the Type IIA eight derivative
one-loop stringy corrections focusing on the couplings of the four dimensional
gravity multiplet with vector multiplets and a tensor multiplet containing the
NS two-form. We obtain a variety of higher derivative invariants generalising
the one-loop topological string coupling, , controlled by the lowest order
Kahler potential and two new non-topological quantities built out of the
Calabi-Yau Riemann curvature.Comment: 43 page
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