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25
Dbrane Spectrum and Ktheory Constraints of D = 4, N =1 Orientifolds
, 2006
"... We study the spectrum of stable BPS and nonBPS Dbranes in Z2 × Z2 orientifolds for all choices of discrete torsion between the orbifold and orientifold generators. We compute the torsion Ktheory charges in these D = 4, N = 1 orientifold models directly from worldsheet conformal field theory, and ..."
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We study the spectrum of stable BPS and nonBPS Dbranes in Z2 × Z2 orientifolds for all choices of discrete torsion between the orbifold and orientifold generators. We compute the torsion Ktheory charges in these D = 4, N = 1 orientifold models directly from worldsheet conformal field theory, and compare with the Ktheory constraints obtained indirectly using Dbrane probes. The Ktheory torsion charges derived here provide nontrivial constraints on string model building. We also discuss regions of stability for nonBPS Dbranes in these examples.
Discrete torsion, nonAbelian orbifolds and the Schur multiplier,” hepth/0010023
"... Preprint typeset in JHEP style. HYPER VERSION ..."
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Open strings in simple current orbifolds
"... We study branes and open strings in a large class of orbifold backgrounds using microscopic techniques of boundary conformal field theory. In particular, we obtain factorizing operator product expansions of open string vertex operators for such branes. Applications include branes in Z2 orbifolds of ..."
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Cited by 11 (2 self)
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We study branes and open strings in a large class of orbifold backgrounds using microscopic techniques of boundary conformal field theory. In particular, we obtain factorizing operator product expansions of open string vertex operators for such branes. Applications include branes in Z2 orbifolds of the SU(2) WZW model and in the Dseries of unitary minimal models considered previously by Runkel.
On Algebraic Singularities, Finite Graphs and DBrane Gauge Theories: A String Theoretic Perspective
, 2002
"... In this writing we shall address certain beautiful interrelations between the construction of 4dimensional supersymmetric gauge theories and resolution of algebraic singularities, from the perspective of String Theory. We review in some detail the requisite background in both the mathematics, such ..."
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Cited by 11 (8 self)
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In this writing we shall address certain beautiful interrelations between the construction of 4dimensional supersymmetric gauge theories and resolution of algebraic singularities, from the perspective of String Theory. We review in some detail the requisite background in both the mathematics, such as orbifolds, symplectic quotients and quiver representations, as well as the physics, such as gauged linear sigma models, geometrical engineering, HananyWitten setups and Dbrane probes. We investigate aspects of worldvolume gauge dynamics using Dbrane resolutions of various CalabiYau singularities, notably Gorenstein quotients and toric singularities. Attention will be paid to the general methodology of constructing gauge theories for these singular backgrounds, with and without the presence of the NSNS Bfield, as well as the Tduals to brane setups and branes wrapping cycles in the mirror geometry. Applications of such diverse and elegant mathematics as crepant resolution of algebraic singularities, representation of finite groups and finite graphs, modular invariants of affine Lie algebras, etc. will naturally arise. Various viewpoints and generalisations of McKay’s Correspondence will also be considered. The present work is a transcription of excerpts from the first three volumes of the author’s PhD thesis which was written under the direction of Prof. A. Hanany to whom he is much indebted at the Centre for Theoretical Physics of MIT, and which, at the suggestion of friends, he posts to the ArXiv pro hac vice; it is his sincerest wish that the ensuing pages might be of some small use to the beginning student.
Discrete Torsion, Covering Groups and Quiver Diagrams
, 2001
"... Preprint typeset in JHEP style. HYPER VERSION ..."
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Gauge Thresholds and Kähler Metrics for Rigid Intersecting Dbrane Models
 JHEP
"... The gauge threshold corrections for globally consistent Z2 ×Z ′ 2 orientifolds with rigid intersecting D6branes are computed. The oneloop corrections to the holomorphic gauge kinetic function are extracted and the Kähler ..."
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Cited by 6 (0 self)
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The gauge threshold corrections for globally consistent Z2 ×Z ′ 2 orientifolds with rigid intersecting D6branes are computed. The oneloop corrections to the holomorphic gauge kinetic function are extracted and the Kähler
Monstrous branes
"... We study Dbranes in the bosonic closed string theory whose automorphism group is the Bimonster group (the wreath product of the Monster simple group with Z2). We give a complete classification of Dbranes preserving the chiral subalgebra of Monster invariants and show that they transform in a repre ..."
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Cited by 2 (1 self)
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We study Dbranes in the bosonic closed string theory whose automorphism group is the Bimonster group (the wreath product of the Monster simple group with Z2). We give a complete classification of Dbranes preserving the chiral subalgebra of Monster invariants and show that they transform in a representation of the Bimonster. Our results apply more generally to selfdual conformal field theories which admit the action of a compact Lie group on both the left and rightmoving sectors.
Dbranes in nonabelian orbifolds with discrete torsion
, 2001
"... hepth/0109170 ..."
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