Results 11  20
of
38
String theory in β deformed spacetimes
 JHEP
, 2005
"... Fluxbranelike backgrounds obtained from flat space by a sequence of Tdualities and shifts of polar coordinates (β deformations) provide an interesting class of exactly solvable string theories. We compute the oneloop partition function for various such deformed spaces and study their spectrum of ..."
Abstract

Cited by 6 (0 self)
 Add to MetaCart
(Show Context)
Fluxbranelike backgrounds obtained from flat space by a sequence of Tdualities and shifts of polar coordinates (β deformations) provide an interesting class of exactly solvable string theories. We compute the oneloop partition function for various such deformed spaces and study their spectrum of Dbranes. For rational values of the Bfield these models are equivalent to ZN × ZN orbifolds with discrete torsion. We also obtain an interesting new class of timedependent backgrounds which resemble localized closed string
On orientifolds, discrete torsion, branes and M theory,” hepth/0003025
"... Abstract: We find some lifts to M theory of orientifold and orbifold planes including the O1, O3 and O5 planes of Type IIB and their transformations under SL(2,Z). The possible discrete torsion variants (or K theory classes) are explored, and are interpreted as arising from brane intersections with ..."
Abstract

Cited by 5 (1 self)
 Add to MetaCart
Abstract: We find some lifts to M theory of orientifold and orbifold planes including the O1, O3 and O5 planes of Type IIB and their transformations under SL(2,Z). The possible discrete torsion variants (or K theory classes) are explored, and are interpreted as arising from brane intersections with planes. We find new variants of the O0 and of an orbifold line (OF1) and determine their tensions in some cases. A review of orientifolds, M orientifolds, and known M lifts, is included together with a discussion of the role of T duality. Keywords: Mtheory, pbranes. 1
Dbranes in nonabelian orbifolds with discrete torsion
, 2001
"... hepth/0109170 ..."
(Show Context)
NonCommutative CalabiYau Manifolds
, 2008
"... We discuss aspects of the algebraic geometry of compact noncommutative CalabiYau manifolds. In this setting, it is appropriate to consider local holomorphic algebras which can be glued together into a compact CalabiYau algebra. We consider two examples: a toroidal orbifold T 6 /Z2 ×Z2, and an orb ..."
Abstract

Cited by 1 (0 self)
 Add to MetaCart
(Show Context)
We discuss aspects of the algebraic geometry of compact noncommutative CalabiYau manifolds. In this setting, it is appropriate to consider local holomorphic algebras which can be glued together into a compact CalabiYau algebra. We consider two examples: a toroidal orbifold T 6 /Z2 ×Z2, and an orbifold of the quintic in CP4, each with discrete torsion. The noncommutative geometry tools are enough to describe various properties of the orbifolds. First, one describes correctly the fractionation of branes at singularities. Secondly, for the first example we show that one can recover explicitly a large slice of the moduli space of complex structures which deform the orbifold. For this example we also show that we get the correct counting of complex structure deformations at the orbifold point by using traces of noncommutative differential forms (cyclic homology).
Discrete torsion orbifolds and Dbranes. ii,” hepth/0101143
"... The consistency of the orbifold action on open strings between Dbranes in orbifold theories with and without discrete torsion is analysed carefully. For the example of the C 3 / Z2 × Z2 theory, it is found that the consistency of the orbifold action requires that the Dbrane spectrum contains brane ..."
Abstract

Cited by 1 (0 self)
 Add to MetaCart
The consistency of the orbifold action on open strings between Dbranes in orbifold theories with and without discrete torsion is analysed carefully. For the example of the C 3 / Z2 × Z2 theory, it is found that the consistency of the orbifold action requires that the Dbrane spectrum contains branes that give rise to a conventional representation of the orbifold group as well as branes for which the representation is projective. It is also shown how the results generalise to the orbifolds C 3 / ZN × ZN, for which a number of novel features arise. In particular, the N> 2 theories with minimal discrete torsion have nonBPS branes charged under twisted RR potentials that couple to none of the (known) BPS branes.
Aspects of ABJM orbifolds
, 2009
"... We study abelian and nonabelian orbifolds of the ABJM model. We compute the precise moduli space of these models by analyzing the classical BPS equations for the theory on the cylinder, which include classical solutions of magnetic monopole operators. These determine the chiral ring of the theory, ..."
Abstract
 Add to MetaCart
We study abelian and nonabelian orbifolds of the ABJM model. We compute the precise moduli space of these models by analyzing the classical BPS equations for the theory on the cylinder, which include classical solutions of magnetic monopole operators. These determine the chiral ring of the theory, and thus they provide the complete set of order parameters determining the classical vacua of the theory. We show that the proper quantization of these semiclassical solutions gives us the topology of moduli space, including the additional quotient information due to the ChernSimons levels. In general, we find that in the dual Mtheory setup, the Mtheory fiber is divided by the product of the ChernSimons level times the order of the orbifold group, even in the nonabelian case. This depends nontrivially on how the different ChernSimons terms have different levels in these constructions. We also see a direct relation in this setup between the ChernSimons levels of the different groups and fluxes for fractional brane cycles. We also show that the problem of the moduli space can be much more easily analyzed by using the method of images and representation theory of crossed product algebras rather than dealing only with the quiver theory data.
Notes on discrete torsion in orientifolds
, 2009
"... In this short note we discuss discrete torsion in orientifolds. In particular, we apply the physical understanding of discrete torsion worked out several years ago, as group actions on B fields, to the case of orientifolds, and recover some old results of Braun and Stefanski concerning group cohomol ..."
Abstract
 Add to MetaCart
(Show Context)
In this short note we discuss discrete torsion in orientifolds. In particular, we apply the physical understanding of discrete torsion worked out several years ago, as group actions on B fields, to the case of orientifolds, and recover some old results of Braun and Stefanski concerning group cohomology and twisted equivariant K theory. We also derive new results
Discrete Torsion and Shift Orbifolds
, 2003
"... In this paper we make two observations related to discrete torsion. First, we observe that an old obscure degree of freedom (momentum/translation shifts) in (symmetric) string orbifolds is related to discrete torsion. We point out how our previous derivation of discrete torsion from orbifold group a ..."
Abstract
 Add to MetaCart
In this paper we make two observations related to discrete torsion. First, we observe that an old obscure degree of freedom (momentum/translation shifts) in (symmetric) string orbifolds is related to discrete torsion. We point out how our previous derivation of discrete torsion from orbifold group actions on B fields includes these momentum lattice shift phases, and discuss how they are realized in terms of orbifold group actions on Dbranes. Second, we describe the M theory dual of IIA discrete torsion, a duality relation to our knowledge not previously understood. We show that IIA discrete torsion is encoded in analogues of the
Lectures on Branes in Curved Backgrounds
 LECTURES PRESENTED AT THE THIRD RTN SCHOOL ON ‘THE QUANTUM STRUCTURE OF SPACETIME
, 2002
"... These lectures provide an introduction to the microscopic description of branes in curved backgrounds. After a brief reminder of the flat space theory, the basic principles and techniques of (rational) boundary conformal field theory are presented in the second lecture. The general formalism is then ..."
Abstract
 Add to MetaCart
(Show Context)
These lectures provide an introduction to the microscopic description of branes in curved backgrounds. After a brief reminder of the flat space theory, the basic principles and techniques of (rational) boundary conformal field theory are presented in the second lecture. The general formalism is then illustrated through a detailed discussion of branes on compact group manifolds. In the final lecture, many more recent developments are reviewed, including some results for noncompact target spaces.