5,499 research outputs found
Conformal Compensators and Manifest Type IIB S-Duality
Using the conformal compensator superfields of N=2 D=4 supergravity, the Type
IIB S-duality transformations are expressed as a linear rotation which mixes
the compensator and matter superfields. The classical superspace action for D=4
compactifications of Type IIB supergravity is manifestly invariant under this
transformation. Furthermore, the introduction of conformal compensators allows
a Fradkin-Tseytlin term to be added to the manifestly SL(2,Z)-covariant sigma
model action of Townsend and Cederwall.Comment: Added references to Cecotti et al, Ferrara et al, and de Wit et a
Anomalies and Graded Coisotropic Branes
We compute the anomaly of the axial U(1) current in the A-model on a
Calabi-Yau manifold, in the presence of coisotropic branes discovered by
Kapustin and Orlov. Our results relate the anomaly-free condition to a recently
proposed definition of graded coisotropic branes in Calabi-Yau manifolds. More
specifically, we find that a coisotropic brane is anomaly-free if and only if
it is gradable. We also comment on a different grading for coisotropic
submanifolds introduced recently by Oh.Comment: AMS Tex, 11 page
S^1 \times S^2 as a bag membrane and its Einstein-Weyl geometry
In the hybrid skyrmion in which an Anti-de Sitter bag is imbedded into the
skyrmion configuration a S^{1}\times S^{2} membrane is lying on the
compactified spatial infinity of the bag [H. Rosu, Nuovo Cimento B 108, 313
(1993)]. The connection between the quark degrees of freedom and the mesonic
ones is made through the membrane, in a way that should still be clarified from
the standpoint of general relativity and topology. The S^1 \times S^2 membrane
as a 3-dimensional manifold is at the same time a Weyl-Einstein space. We make
here an excursion through the mathematical body of knowledge in the
differential geometry and topology of these spaces which is expected to be
useful for hadronic membranesComment: 9pp in latex, minor correction
Calabi--Yau complete intersections in exceptional Grassmannians
We classify completely reducible equivariant vector bundles on Grassmannians
of exceptional Lie groups which give Calabi--Yau 3-folds as complete
intersections. In particular, we find a new family of Calabi--Yau 3-folds in an
-Grassmannian.Comment: 10 pages, minor revisio
Quotients of E^n by A_{n+1} and Calabi-Yau manifolds
We give a simple construction, starting with any elliptic curve E, of an
n-dimensional Calabi-Yau variety of Kummer type (for any n>1), by considering
the quotient Y of the n-fold self-product of E by a natural action of the
alternating group A_{n+1} (in n+1 variables). The vanishing of H^m(Y, O_Y) for
0<m<n follows from the non-existence of (non-zero) fixed points in certain
representations of A_{n+1}. For n<4 we provide an explicit crepant resolution X
in characteristics different from 2,3. The key point is that Y can be realized
as a double cover of P^n branched along a hypersurface of degree 2(n+1).Comment: 9 page
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