6,157 research outputs found
D6-brane Splitting on Type IIA Orientifolds
We study the open-string moduli of supersymmetric D6-branes, addressing both
the string and field theory aspects of D6-brane splitting on Type IIA
orientifolds induced by open-string moduli Higgsing (i.e., their obtaining
VEVs). Specifically, we focus on the Z_2 x Z_2 orientifolds and address the
symmetry breaking pattern for D6-branes parallel with the orientifold 6-planes
as well as those positioned at angles. We demonstrate that the string theory
results, i.e., D6-brane splitting and relocating in internal space, are in one
to one correspondence with the field theory results associated with the
Higgsing of moduli in the antisymmetric representation of Sp(2N) gauge symmetry
(for branes parallel with orientifold planes) or adjoint representation of U(N)
(for branes at general angles). In particular, the moduli Higgsing in the
open-string sector results in the change of the gauge structure of D6-branes
and thus changes the chiral spectrum and family number as well. As a
by-product, we provide the new examples of the supersymmetric Standard-like
models with the electroweak sector arising from Sp(2N)_L x Sp(2N)_R gauge
symmetry; and one four-family example is free of chiral Standard Model exotics.Comment: 44 pages, 7 figures; The anomaly-free models in Subsections 4.2 and
4.3 presented, references added, typos fixe
Flat 3-webs of degree one on the projective plane
The aim of this work is to study global -webs with vanishing curvature. We
wish to investigate degree foliations for which their dual web is flat. The
main ingredient is the Legendre transform, which is an avatar of classical
projective duality in the realm of differential equations. We find a
characterization of degree foliations whose Legendre transform are webs
with zero curvature.Comment: 14 page
On moduli and effective theory of N=1 warped flux compactifications
The moduli space of N=1 type II warped compactions to flat space with generic
internal fluxes is studied. Using the underlying integrable generalized complex
structure that characterizes these vacua, the different deformations are
classified by H-twisted generalized cohomologies and identified with chiral and
linear multiplets of the effective four-dimensional theory. The Kaehler
potential for chiral fields corresponding to classically flat moduli is
discussed. As an application of the general results, type IIB warped Calabi-Yau
compactifications and other SU(3)-structure subcases are considered in more
detail.Comment: 54 pages; v3: comments and references added, version published in
JHE
D-branes on Fourfolds with Discrete Torsion
We study D1-branes on the fourfold \C^4/(\Z_2\times\Z_2\times\Z_2), in the
presence of discrete torsion. Discrete torsion is incorporated in the gauge
theory of the D1-branes by considering a projective representation of the
finite group . The corresponding orbifold is then
deformed by perturbing the F-flatness condition of the gauge theory. The moduli
space of the resulting gauge theory retains a stable singularity of codimension
three.Comment: Two references adde
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