Results 1  10
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21
CalabiYau connections with torsion on toric bundles
"... We find sufficient conditions for principal toric bundles over compact Kähler manifolds to admit CalabiYau connections with torsion, as well as conditions to admit strong Kähler connections with torsion. With the aid of a topological classification, we construct such geometry on (k −1)(S 2 ×S 4)#k( ..."
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We find sufficient conditions for principal toric bundles over compact Kähler manifolds to admit CalabiYau connections with torsion, as well as conditions to admit strong Kähler connections with torsion. With the aid of a topological classification, we construct such geometry on (k −1)(S 2 ×S 4)#k(S 3 ×S 3) for all k ≥ 1. 1.
Comments on heterotic flux compactifications
 JHEP
"... In heterotic flux compactification with supersymmetry, three different connections with torsion appear naturally, all in the form ω + aH. Supersymmetry condition carries a = −1, the Dirac operator has a = −1/3, and higher order term in the effective action involves a = 1. With a view toward the gaug ..."
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In heterotic flux compactification with supersymmetry, three different connections with torsion appear naturally, all in the form ω + aH. Supersymmetry condition carries a = −1, the Dirac operator has a = −1/3, and higher order term in the effective action involves a = 1. With a view toward the gauge sector, we explore the geometry with such torsions. After reviewing the supersymmetry constraints and finding a relation between the scalar curvature and the flux, we derive the squared form of the zero mode equations for gauge fermions. With dH = 0, the operator has a positive potential term, and the mass of the unbroken gauge sector appears formally positive definite. However, this apparent contradiction is avoided by a nogo theorem that the compactification with H ̸ = 0 and dH = 0 is necessarily singular, and the formal positivity is invalid. With dH ̸ = 0, smooth compactification becomes possible. We show that, at least near supersymmetric solution, the consistent truncation of action has to keep α ′ R 2 term in the effective action. A warp factor equation of motion is rewritten with α ′ R 2 contribution included precisely, and some limits are considered.
Heterotic Resolved Conifolds with Torsion, from Supergravity to
 CFT, JHEP 01 (2010) 083, arXiv:0910.3190 [hepth
"... We obtain a family of heterotic supergravity backgrounds describing nonKähler warped conifolds with threeform flux and an Abelian gauge bundle, preserving N = 1 supersymmetry in four dimensions. At large distance from the singularity the usual Ricciflat conifold is recovered. By performing a Z2 ..."
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Cited by 12 (0 self)
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We obtain a family of heterotic supergravity backgrounds describing nonKähler warped conifolds with threeform flux and an Abelian gauge bundle, preserving N = 1 supersymmetry in four dimensions. At large distance from the singularity the usual Ricciflat conifold is recovered. By performing a Z2 orbifold of the T 1,1 base, the conifold singularity can be blownup to a fourcycle, leading to a completely smooth geometry. Remarkably, the throat regions of the solutions, which can be isolated from the asymptotic Ricciflat geometry using a doublescaling limit, possess a worldsheet CFT description in terms of heterotic cosets whose target space is the warped resolved orbifoldized conifold. Thus this construction provides exact solutions of the modified Bianchi identity. By solving algebraically these CFTs we compute the exact treelevel heterotic string spectrum and describe worldsheet nonperturbative effects. The holographic dual of these solutions, in particular their confining behavior, and the embedding of these fluxed singularities into heterotic compactifications with torsion are also discussed.
Geometric transitions, flops and nonKähler manifolds: I
, 2004
"... We construct a duality cycle which provides a complete supergravity description of geometric transitions in type II theories via a flop in Mtheory. This cycle connects the different supergravity descriptions before and after the geometric transitions. Our construction reproduces many of the known p ..."
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Cited by 11 (6 self)
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We construct a duality cycle which provides a complete supergravity description of geometric transitions in type II theories via a flop in Mtheory. This cycle connects the different supergravity descriptions before and after the geometric transitions. Our construction reproduces many of the known phenomena studied earlier in the literature and allows us to describe some new and interesting aspects in a simple and elegant fashion. A precise supergravity description of new torsional manifolds that appear on the type IIA side with branes and fluxes and the corresponding geometric transition are obtained. A local description of new G2 manifolds that are circle fibrations over nonKähler manifolds
Heterotic standard model moduli
 JHEP
"... In previous papers, we introduced a heterotic standard model and discussed its basic properties. The CalabiYau threefold has, generically, three Kähler and three complex structure moduli. The observable sector of this vacuum has the spectrum of the MSSM with one additional pair of HiggsHiggs conju ..."
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Cited by 11 (9 self)
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In previous papers, we introduced a heterotic standard model and discussed its basic properties. The CalabiYau threefold has, generically, three Kähler and three complex structure moduli. The observable sector of this vacuum has the spectrum of the MSSM with one additional pair of HiggsHiggs conjugate fields. The hidden sector has no charged matter in the strongly coupled string and only minimal matter for weak coupling. Additionally, the spectrum of both sectors will contain vector bundle moduli. The exact number of such moduli was conjectured to be small, but was not explicitly computed. In this paper, we rectify this and present a formalism for computing the number of vector bundle moduli. Using this formalism, the number of moduli in both the observable and strongly coupled
A heterotic flux background and calibrated fivebranes
 JHEP
"... We consider, in flux compactification of heterotic string theory, spacetimefilling fivebranes. Stabilizing the fivebrane involves minimizing the combined energy density of the tension and a Coulomb potential associated with an internal 2dimensional wrapping. After reviewing the generalized calibra ..."
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We consider, in flux compactification of heterotic string theory, spacetimefilling fivebranes. Stabilizing the fivebrane involves minimizing the combined energy density of the tension and a Coulomb potential associated with an internal 2dimensional wrapping. After reviewing the generalized calibration under such circumstances, we consider a particular internal manifold based on a T 2 bundle over a conformally rescaled K3. Here, we find two distinct types of wrapping. In one class, the fivebrane wraps the fibre T 2 which belongs to a cyclic homotopy group. The winding number is not extensive, yet it maps to D3brane number under a Uduality map to type IIB side. We justify this by comparing properties of the two sides in detail. Fivebranes may also wrap a topological 2cycle of K3, by saturating a standard calibration requirement with respect to a closed Kähler 2form JK3 of K3. We close with detailed discussion on Ftheory dual of these objects and related issues.
Index theorems on torsional geometries
 JHEP 0708 (2007) 048 [arXiv:0704.2111
"... We study various topological invariants on a differential geometry in the presence of a totally antisymmetric torsion H under the closed condition dH = 0. By using the identification between the Clifford algebra on a geometry and the canonical quantization condition of fermion in the quantum mechan ..."
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Cited by 8 (1 self)
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We study various topological invariants on a differential geometry in the presence of a totally antisymmetric torsion H under the closed condition dH = 0. By using the identification between the Clifford algebra on a geometry and the canonical quantization condition of fermion in the quantum mechanics, we construct the N = 1 quantum mechanical sigma model in the Hamiltonian formalism and extend this model to N = 2 system, equipped with the totally antisymmetric tensor associated with the torsion on the target space geometry. Next we construct transition elements in the Lagrangian path integral formalism and apply them to the analyses of the Witten indices in supersymmetric systems. We improve the formulation of the Dirac index on the torsional geometry which has already been studied. We also formulate the Euler characteristic and Flux compactification scenarios have become one of the most significant issues in the study of low energy effective theories from string theories (for instance, see [1, 2, 3] and references therein). Nontrivial fluxes induce a superpotential, which stabilizes moduli of a compactified geometry and decreases the number of “redundant ” massless modes in the low energy effective theory in four dimensional
Heterotic String Compactifications on Halfflat Manifolds II
, 709
"... In this paper, we continue the analysis of heterotic string compactifications on halfflat mirror manifolds by including the 10dimensional gauge fields. It is argued, that the heterotic Bianchi identity is solved by a variant of the standard embedding. Then, the resulting gauge group in four dimens ..."
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In this paper, we continue the analysis of heterotic string compactifications on halfflat mirror manifolds by including the 10dimensional gauge fields. It is argued, that the heterotic Bianchi identity is solved by a variant of the standard embedding. Then, the resulting gauge group in four dimensions is still E6 despite the fact that the LeviCivita connection has SO(6) holonomy. We derive the associated fourdimensional effective theories including matter field terms for such compactifications. The results are also extended to more general manifolds with SU(3) structure.