433 research outputs found
A Note on q-Deformed Two-Dimensional Yang-Mills and Open Topological Strings
In this note we make a test of the open topological string version of the OSV
conjecture, proposed in hep-th/0504054, in the toric Calabi-Yau manifold with background D4-branes wrapped on Lagrangian
submanifolds. The D-brane partition function reduces to an expectation value of
some inserted operators of a q-deformed Yang-Mills theory living on a chain of
's in the base of . At large this partition
function can be written as a sum over squares of chiral blocks, which are
related to the open topological string amplitudes in the local
geometry with branes at both the outer and inner edges of the toric diagram.
This is in agreement with the conjecture.Comment: 14 pages, 3 figure
An action for the (2,0) self-dual tensor multiplet in a conformal supergravity background
We present the action for a self-dual tensor in six dimensions, coupled to a
(2,0) conformal supergravity background. This action gives rise to the expected
equations of motion. An alternative look upon one of the gauge symmetries
clarifies its role in the supersymmetry transformation rules and the
realisation of the algebra.Comment: 14 pages, accepted by Class. Quant. Gra
Intersecting Brane Worlds -- A Path to the Standard Model ?
In this review we describe the general geometrical framework of brane world
constructions in orientifolds of type IIA string theory with D6-branes wrapping
3-cycles in a Calabi-Yau 3-fold. These branes generically intersect in points
on the internal space, and the patterns of intersections govern the chiral
fermion spectra. We discuss how the open string spectra in intersecting brane
models are constructed, how the Standard Model can be embedded, and also how
supersymmetry can be realized in this class of string vacua. After the general
considerations we specialize the discussion to the case of orbifold backgrounds
with intersecting D6-branes and to the quintic Calabi-Yau manifold. Then, we
discuss parts of the effective action of intersecting brane world models.
Specifically we compute from the Born-Infeld action of the wrapped D-branes the
tree-level, D-term scalar potential, which is important for the stability of
the considered backgrounds as well as for questions related to supersymmetry
breaking. Second, we review the recent computation concerning of gauge coupling
unification and also of one-loop gauge threshold corrections in intersecting
brane world models. Finally we also discuss some aspects of proton decay in
intersecting brane world models.Comment: 31 pages, To appear in the proceedings of the RTN-workshop ``The
quantum structure of spacetime and the geometric nature of fundamental
interactions'', September 2003 in Copenhagen, revised version contains new
refs and one corrected equatio
Cosmological Supergravity from a Massive Superparticle and Super Cosmological Black Holes
We describe in superspace a classical theory of two dimensional
dilaton supergravity with a cosmological constant, both with and without
coupling to a massive superparticle. We give general exact non-trivial
superspace solutions for the compensator superfield that describes the
supergravity in both cases. We then use these compensator solutions to
construct models of two-dimensional supersymmetric cosmological black holes.Comment: 20 pages, Late
Mirror Symmetry and Landau Ginzburg Calabi-Yau Superpotentials in F-theory Compactifications
We study Landau Ginzburg (LG) theories mirror to 2D N=2 gauged linear sigma
models on toric Calabi-Yau manifolds. We derive and solve new constraint
equations for Landau Ginzburg elliptic Calabi-Yau superpotentials, depending on
the physical data of dual linear sigma models. In Calabi-Yau threefolds case,
we consider two examples. First, we give the mirror symmetry of the canonical
line bundle over the Hirzebruch surfaces . Second, we find a special
geometry with the affine so(8) Lie algebra toric data extending the geometry of
elliptically fibered K3. This geometry leads to a pure N=1 six dimensional
SO(8) gauge model from the F-theory compactification. For Calabi-Yau fourfolds,
we give a new algebraic realization for ADE hypersurfaces.Comment: 27 pages, latex. To appear in Journal of Physics A: Mathematical and
Genera
A New Fractional D2-brane, G_2 Holonomy and T-duality
Recently, a new example of a complete non-compact Ricci-flat metric of G_2
holonomy was constructed, which has an asymptotically locally conical structure
at infinity with a circular direction whose radius stabilises. In this paper we
find a regular harmonic 3-form in this metric, which we then use in order to
obtain an explicit solution for a fractional D2-brane configuration. By
performing a T-duality transformation on the stabilised circle, we obtain the
type IIB description of the fractional brane, which now corresponds to D3-brane
with one of its world-volume directions wrapped around the circle.Comment: Latex, 13 page
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