相关论文: Strings on Orbifold Lines

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…

We present non-supersymmetric toroidal compactifications of type I string theory with both constant background NSNS two-form flux and non-trivial magnetic flux on the various D9-branes. The non-vanishing B-flux admits four-dimensional…

We introduce a new class of non-compact backgrounds of Type IIB string theory preserving eight supercharges by combining S-folds and non-perturbative 7-branes wrapping orbifolds, and study the four-dimensional superconformal field theories…

We consider type IIA/B strings in two-dimensions and their projection with respect to the nilpotent space-time supercharge. Based on the ground ring structure, we propose a duality between perturbed type II strings and the topological…

We find the exact spectrum of a class of quarter BPS dyons in a generic N=4 supersymmetric Z_N orbifold of type IIA string theory on K3\times T^2 or T^6. We also find the asymptotic expansion of the statistical entropy to first non-leading…

We study the stringy instanton partition function of four dimensional ${\cal N}=2$ $U(N)$ supersymmetric gauge theory which was obtained by Bonelli et al in 2013. In type IIB string theory on $\mathbb{C}^2\times T^*\mathbb{P}^1\times…

It is shown that the orbifold of type IIB string theory by (-1)^{F_L} I_4 admits a stable non-BPS Dirichlet particle that is stuck on the orbifold fixed plane. It is charged under the SO(2) gauge group coming from the twisted sector, and…

S-duality symmetry of type IIB string theory predicts the existence of a stable non-BPS state on an orbifold five plane of the type IIB theory if the orbifold group is generated by the simultaneous action of (-1)^{F_L} and the reversal of…

We analyse the symmetries of a class of A-type little string theories that are engineered by $N$ parallel M5-branes with M2-branes stretched between them. This paper deals with the so-called reduced free energy, which only receives…

In theories with extended supersymmetry the protected observables of UV superconformal fixed points are found in a number of contexts to be encoded in the BPS solitons along an IR Coulomb-like phase. For six-dimensional SCFTs such a role is…

We describe the fate of the Type I non-BPS D7-brane, which is tachyonic but carries a non-trivial K-theory $\IZ_2$ charge. It decays to topologically non-trivial gauge field configurations on the background D9-branes. In the uncompactified…

We study freely acting orbifolds of type IIB string theory on $T^5$ that spontaneously break supersymmetry from $\mathcal{N}=8$ to $\mathcal{N}=6,4,2$ or 0 in five dimensions. We focus on orbifolds that are a $\mathbb{Z}_p$ quotient by a…

In this dissertation, we study various aspects of type IIB string theory compactified on freely acting orbifolds. We focus particularly on asymmetric orbifolds, which are examples of non-geometric string compactifications and constitute an…

Motivated by the string theory analysis of arXiv:1108.6331, we construct a class of 1/8-BPS solutions of type IIB supergravity compactified on S^1 x T^4. In this duality frame our ansatz allows for a non-trivial NS-NS B-field which has been…

We study the spectrum of stable BPS and non-BPS D-branes in Z_2 x Z_2 orientifolds for all choices of discrete torsion between the orbifold and orientifold generators. We compute the torsion K-theory charges in these D=4, N=1 orientifold…

We construct bosonic string theories, RNS string theories and heterotic string theories on flat supermanifolds. For these string theories, we show cancellations of the central charges and modular invariance. Bosonic string theories on…

We study the spectrum of BPS D5-D3-F1 states in type IIB theory, which are proposed to be dual to D4-D2-D0 states on the resolved conifold in type IIA theory. We evaluate the BPS partition functions for all values of the moduli parameter in…

We study the 2d N = 4 gauge theory descriptions of little strings on type II NS5- branes. The IIB strings on N NS5-branes are described by the N = (4,4) gauge theories, whose Higgs branch CFTs on U(N) instanton moduli spaces are relevant.…

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…

It has been recently shown that F-theory on K3 with background B fields (NSNS and RR 2-forms) is dual to the CHL string in 8 dimensions. In this paper, we reexamine this duality in terms of string junctions in type IIB string theory. It is…