Results 11  20
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60
Heterotic flux compactifications and their moduli
, 2006
"... We study supersymmetric compactification to four dimensions with nonzero Hflux in heterotic string theory. The background metric is generically conformally balanced and can be conformally Kähler if the primitive part of the Hflux vanishes. Analyzing the linearized variational equations, we write ..."
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Cited by 21 (3 self)
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We study supersymmetric compactification to four dimensions with nonzero Hflux in heterotic string theory. The background metric is generically conformally balanced and can be conformally Kähler if the primitive part of the Hflux vanishes. Analyzing the linearized variational equations, we write down necessary conditions for the existence of moduli associated with the metric. In a heterotic model that is dual to a IIB compactification on an orientifold, we find the metric moduli in a fixed Hflux background via duality and check that they satisfy the required conditions. We also discuss expressing the conditions for moduli in a fixed flux background using twisted differential operators.
KT and HKT geometries in strings and black hole moduli spaces
"... Some selected applications of KT and HKT geometries in string theory, supergravity, black hole moduli spaces and hermitian geometry are reviewed. It is shown that the moduli spaces of a large class of fivedimensional supersymmetric black holes are HKT spaces. In hermitian geometry, it is shown that ..."
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Cited by 12 (0 self)
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Some selected applications of KT and HKT geometries in string theory, supergravity, black hole moduli spaces and hermitian geometry are reviewed. It is shown that the moduli spaces of a large class of fivedimensional supersymmetric black holes are HKT spaces. In hermitian geometry, it is shown that a compact, conformally balanced, strong KT manifold whose associated KT connection has holonomy contained in SU(n) is CalabiYau. The implication of this result in the context of some string compactifications is explained
Supersymmetric heterotic string backgrounds
, 2007
"... We present the main features of the solution of the gravitino and dilatino Killing spinor equations derived in hepth/0510176 and hepth/0703143 which have led to the classification of geometric types of all type I backgrounds. We then apply these results to the supersymmetric backgrounds of the het ..."
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Cited by 12 (2 self)
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We present the main features of the solution of the gravitino and dilatino Killing spinor equations derived in hepth/0510176 and hepth/0703143 which have led to the classification of geometric types of all type I backgrounds. We then apply these results to the supersymmetric backgrounds of the heterotic string. In particular, we solve the gaugino Killing spinor equation together with the other two Killing spinor equations of the theory. We also use our results to classify all supersymmetry conditions of tendimensional gauge theory.
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
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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Cited by 9 (0 self)
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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.
On asthenoKähler metrics
"... Abstract. A Hermitian metric on a complex manifold of complex dimension n is called asthenoKähler if its fundamental 2form F satisfies the condition ∂∂F n−2 = 0 and it is strong KT if F is ∂∂closed. We prove that a conformally balanced asthenoKähler metric on a compact manifod of complex dimensi ..."
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Cited by 8 (1 self)
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Abstract. A Hermitian metric on a complex manifold of complex dimension n is called asthenoKähler if its fundamental 2form F satisfies the condition ∂∂F n−2 = 0 and it is strong KT if F is ∂∂closed. We prove that a conformally balanced asthenoKähler metric on a compact manifod of complex dimension n ≥ 3, whose Bismut connection has (restricted) holonomy contained in SU(n), is necessarily Kähler. We provide compact examples of locally conformally balanced asthenoKähler manifolds of complex dimension 3 for which the trace of R B ∧R B vanishes, where R B is the curvature of their Bismut connection. We study blowups of asthenoKähler manifolds for which ∂∂F = 0 and ∂∂F 2 = 0 and we apply these results to orbifolds. Finally, we construct a family of asthenoKähler 2step nilmanifolds of complex dimension 4, showing that, in general, for n> 3, there is no relation between the asthenoKähler and strong KT condition. 1.
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
NonKaehler Heterotic String Compactifications with nonzero fluxes and constant dilaton
, 2008
"... We construct new explicit compact valid solutions with nonzero field strength and constant dilaton to the heterotic string equations in dimension six. We present balanced Hermitian structures on compact nilmanifolds in dimension six satisfying the heterotic supersymmetry equations with nonzero f ..."
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Cited by 7 (3 self)
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We construct new explicit compact valid solutions with nonzero field strength and constant dilaton to the heterotic string equations in dimension six. We present balanced Hermitian structures on compact nilmanifolds in dimension six satisfying the heterotic supersymmetry equations with nonzero flux and constant dilaton which obey the threeform Bianchi identity with curvature term taken with respect to either the LeviCivita, the (+)connection or the Chern connection.