Related papers: Flat Directions in $Z_{2n}$ Orbifold Models
We resolve a puzzle in the theory of strings propagating on locally flat spacetimes with nontrivial Wilson lines for stringy Z_N gauge symmetries. We find that strings probing such backgrounds are described by consistent worldsheet CFTs.…
We analyse various two dimensional theories arising from compactification of type II and heterotic string theory on asymmetric orbifolds. We find extra supersymmetry generators arising from twisted sectors, giving rise to exotic…
For a large class of $N=2$ SCFTs, which includes minimal models and many $\s$ models on Calabi-Yau manifolds, the mirror theory can be obtained as an orbifold. We show that in such a situation the construction of the mirror can be extended…
We provide the general tadpole conditions for a class of supersymmetric orientifold models by studing the general properties of the elements included in the orientifold group. In this talk, we concentrate on orientifold models of the type…
We show how identification of absolutely flat directions allows the construction of a new class of compactified string theories with reduced gauge symmetry that may or may not be continuously connected to the original theory. We use this…
We present the coset structure of the untwisted moduli space of heterotic $(0,2) \; Z_N$ orbifold compactifications with continuous Wilson lines. For the cases where the internal 6-torus $T_6$ is given by the direct sum $T_4 \oplus T_2$, we…
We extend the methods of Davis-Januszkiewicz-Lafont to provide a new obstruction to smooth Riemannian metric with non-positive sectional curvature. We construct examples of locally CAT(0) 4-manifolds $M$, whose universal covers satisfy…
This paper is about the orbifold theory for vertex operator superalgebras. Given a vertex operator superalgebra V and a finite automorphism group G of V, we show that the trace functions associated to the twisted sectors are holomorphic in…
Using free world-sheet fermions, we construct and classify all the N=2, Z2 X Z2 four-dimensional orbifolds of the type IIA/B strings for which the orbifold projections act symmetrically on the left and right movers. We study the…
The dynamics of $\mathcal{N}=1$ SUSY gauge theories with matter in adjoint and fundamental representations and the superpotentials given by Arnold's ADE singularities has been extensively studied in the literature. It was also conjectured…
We investigate four-dimensional N=1 Type IIB orientifolds with continuous Wilson lines, and their T-dual realizations as orientifolds with moving branes. When continuous Wilson lines become discrete the gauge symmetry is enhanced and the…
Six dimensional compactification of the type IIA matrix model on the ${\bf Z}$-orbifold is studied. Introducing a ${\bf Z}_{3}$ symmetry properly on the three mirror images of fields in the $N$-body system of the supersymmetric D0…
We analyze unoriented Wess-Zumino-Witten models from a geometrical point of view. We show that the geometric interpretation of simple current crosscap states is as centre orientifold planes localized on conjugacy classes of the group…
The $Z_2\times Z_2$ heterotic string orbifold gives rise to a large space of phenomenological three generation models that serves as a testing ground to explore how the Standard Model of particle physics may be incorporated in a theory of…
We attempt to deal with the orbifold singularities in the moduli space of flat connections for supersymmetric gauge theories on the torus. The fields are restricted to the fundamental domain, containing no gauge copies, but requiring a…
We revisit type I compactifications with a Spin(32)/Z2 gauge bundle that admits no vector structure. We elucidate the relation of this Z2 obstruction to discrete B-field flux and to 't Hooft flux and clarify some subtleties in the T-duality…
Orbifolding two-dimensional quantum field theories by a symmetry group can involve a choice of discrete torsion. We apply the general formalism of `orbifolding defects' to study and elucidate discrete torsion for topological field theories.…
For a compact Riemann surface X of positive genus, the space of sections of certain theta bundle on moduli of bundles of rank r and level k admits a natural map to (the dual of) a similar space of sections of rank k and level r (the strange…
The main goal of this article is to construct some geometric invariants for the topology of the set $\mathcal{F}$ of flat connections on a principal $G$-bundle $P\,\longrightarrow\, M$. Although the characteristic classes of principal…
We construct compact type IIB orientifolds with discrete groups Z_4, Z_6, Z_6', Z_8, Z_12 and Z_12'. These models are N=1 supersymmetric in D=4 and have vector structure. The possibility of having vector structure in Z_N orientifolds with…