282 research outputs found
Open mirror symmetry for Pfaffian Calabi-Yau 3-folds
We investigate the open mirror symmetry of certain non-complete intersection
Calabi- Yau 3-folds, so called pfaffian Calabi-Yau. We perform the prediction
of the number of disk invariants of several examples by using the direct
integration method proposed recently and the open mirror symmetry. We treat
several pfaffian Calabi-Yau 3-folds in and branes with two
discrete vacua. Some models have the two special points in its moduli space,
around both of which we can consider different A-model mirror partners. We
compute disc invariants for both cases. This study is the first application of
the open mirror symmetry to the compact non-complete intersections in toric
variety.Comment: 64 pages; v2: typos corrected, minor changes, references added; v3:
published version, minor corrections and improvement
The effective action of D6-branes in N=1 type IIA orientifolds
We use a Kaluza-Klein reduction to compute the low-energy effective action
for the massless modes of a spacetime-filling D6-brane wrapped on a special
Lagrangian 3-cycle of a type IIA Calabi-Yau orientifold. The modifications to
the characteristic data of the N=1 bulk orientifold theory in the presence of a
D6-brane are analysed by studying the underlying Type IIA supergravity coupled
to the brane worldvolume in the democratic formulation and performing a
detailed dualisation procedure. The N=1 chiral coordinates are found to be in
agreement with expectations from mirror symmetry. We work out the Kahler
potential for the chiral superfields as well as the gauge kinetic functions for
the bulk and the brane gauge multiplets including the kinetic mixing between
the two. The scalar potential resulting from the dualisation procedure can be
formally interpreted in terms of a superpotential. Finally, the gauging of the
Peccei-Quinn shift symmetries of the complex structure multiplets reproduces
the D-term potential enforcing the calibration condition for special Lagrangian
3-cycles.Comment: 48 pages, v2: typos corrected, references adde
Remarks on quiver gauge theories from open topological string theory
We study effective quiver gauge theories arising from a stack of D3-branes on certain Calabi-Yau singularities. Our point of view is a first principle approach via open topological string theory. This means that we construct the natural A-infinity-structure of open string amplitudes in the associated D-brane category. Then we show that it precisely reproduces the results of the method of brane tilings, without having to resort to any effective field theory computations. In particular, we prove a general and simple formula for effective superpotentials
Maximal Temperature in Flux Compactifications
Thermal corrections have an important effect on moduli stabilization leading
to the existence of a maximal temperature, beyond which the compact dimensions
decompactify. In this note, we discuss generality of our earlier analysis and
apply it to the case of flux compactifications. The maximal temperature is
again found to be controlled by the supersymmetry breaking scale, T_{crit} \sim
\sqrt{m_{3/2} M_P}.Comment: 10 pages, 10 figures. v2:comment and references adde
Combined BIMA and OVRO observations of comet C/1999 S4 (LINEAR)
We present results from an observing campaign of the molecular content of the
coma of comet C/1999 S4 (LINEAR) carried out jointly with the millimeter-arrays
of the Berkeley-Illinois-Maryland Association (BIMA) and the Owens Valley Radio
Observatory (OVRO). Using the BIMA array in autocorrelation (`single-dish')
mode, we detected weak HCN J=1-0 emission from comet C/1999 S4 (LINEAR) at 14
+- 4 mK km/s averaged over the 143" beam. The three days over which emission
was detected, 2000 July 21.9-24.2, immediately precede the reported full
breakup of the nucleus of this comet. During this same period, we find an upper
limit for HCN 1-0 of 144 mJy/beam km/s (203 mK km/s) in the 9"x12" synthesized
beam of combined observations of BIMA and OVRO in cross-correlation (`imaging')
mode. Together with reported values of HCN 1-0 emission in the 28" IRAM
30-meter beam, our data probe the spatial distribution of the HCN emission from
radii of 1300 to 19,000 km. Using literature results of HCN excitation in
cometary comae, we find that the relative line fluxes in the 12"x9", 28" and
143" beams are consistent with expectations for a nuclear source of HCN and
expansion of the volatile gases and evaporating icy grains following a Haser
model.Comment: 18 pages, 3 figures. Uses aastex. AJ in pres
Five-Brane Superpotentials, Blow-Up Geometries and SU(3) Structure Manifolds
We investigate the dynamics of space-time filling five-branes wrapped on
curves in heterotic and orientifold Calabi-Yau compactifications. We first
study the leading N=1 scalar potential on the infinite deformation space of the
brane-curve around a supersymmetric configuration. The higher order potential
is also determined by a brane superpotential which we compute for a subset of
light deformations. We argue that these deformations map to new complex
structure deformations of a non-Calabi-Yau manifold which is obtained by
blowing up the brane-curve into a four-cycle and by replacing the brane by
background fluxes. This translates the original brane-bulk system into a
unifying geometrical formulation. Using this blow-up geometry we compute the
complete set of open-closed Picard-Fuchs differential equations and identify
the brane superpotential at special points in the field space for five-branes
in toric Calabi-Yau hypersurfaces. This has an interpretation in open mirror
symmetry and enables us to list compact disk instanton invariants. As a first
step towards promoting the blow-up geometry to a supersymmetric heterotic
background we propose a non-Kaehler SU(3) structure and an identification of
the three-form flux.Comment: 95 pages, 4 figures; v2: Minor corrections, references update
Decoupling A and B model in open string theory -- Topological adventures in the world of tadpoles
In this paper we analyze the problem of tadpole cancellation in open
topological strings. We prove that the inclusion of unorientable worldsheet
diagrams guarantees a consistent decoupling of A and B model for open
superstring amplitudes at all genera. This is proven by direct microscopic
computation in Super Conformal Field Theory. For the B-model we explicitly
calculate one loop amplitudes in terms of analytic Ray-Singer torsions of
appropriate vector bundles and obtain that the decoupling corresponds to the
cancellation of D-brane and orientifold charges. Local tadpole cancellation on
the worldsheet then guarantees the decoupling at all loops. The holomorphic
anomaly equations for open topological strings at one loop are also obtained
and compared with the results of the Quillen formula
Non-Perturbative Superpotentials in F-theory and String Duality
We use open-closed string duality between F-theory on K3xK3 and type II
strings on CY manifolds without branes to study non-perturbative
superpotentials in generalized flux compactifications. On the F-theory side we
obtain the full flux potential including D3-instanton contributions and show
that it leads to an explicit and simple realization of the three ingredients of
the KKLT model for stringy dS vacua. The D3-instanton contribution is highly
non-trivial, can be systematically computed including the determinant factors
and demonstrates that a particular flux lifts very effectively zero modes on
the instanton. On the closed string side, we propose a generalization of the
Gukov-Vafa-Witten superpotential for type II strings on generalized CY
manifolds, depending on all moduli multiplets.Comment: 49 pages, harvmac, 1 figure; references & figures adde
Effective superpotentials for compact D5-brane Calabi-Yau geometries
For compact Calabi-Yau geometries with D5-branes we study N=1 effective
superpotentials depending on both open- and closed-string fields. We develop
methods to derive the open/closed Picard-Fuchs differential equations, which
control D5-brane deformations as well as complex structure deformations of the
compact Calabi-Yau space. Their solutions encode the flat open/closed
coordinates and the effective superpotential. For two explicit examples of
compact D5-brane Calabi-Yau hypersurface geometries we apply our techniques and
express the calculated superpotentials in terms of flat open/closed
coordinates. By evaluating these superpotentials at their critical points we
reproduce the domain wall tensions that have recently appeared in the
literature. Finally we extract orbifold disk invariants from the
superpotentials, which, up to overall numerical normalizations, correspond to
orbifold disk Gromov-Witten invariants in the mirror geometry.Comment: 55 pages; v2: references added, typos correcte
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