相关论文: Non-standard embedding and five-branes in heteroti…

We study N=1 dualities in four dimensional supersymmetric gauge theories by D 6-branes wrapping around 3-cycles of Calabi-Yau threefolds in the type IIA string theory. We consider the models involving $SU(N_{c1})\times SU(N_{c2})$ product…

We consider the low-energy limit of the two-dimensional theory on k M2-branes suspended between a straight M5-brane and a curved M5-brane. We argue that it is described by an N=(2,2) supersymmetric gauge theory with no matter fields but…

We present explicit methods for computing the discriminant curves and the associated Kodaira type fiber degeneracies of elliptically fibered Calabi-Yau threefolds. These methods are applied to a specific three-family, SU(5) grand unified…

Basics of some topics on perturbative and non-perturbative string theory are reviewed. After a mathematical survey of the Standard Model of particle physics and GUTs, the bosonic string kinematics for the free case and with interaction is…

We study the effective low energy supergravity of the strongly coupled heterotic string compactified on a Calabi-Yau 3-fold with generic E8 x E8 gauge bundle. We focus on the effective potential for the chiral scalars. The effective…

We use the method of stable degenerations to study the local geometry of Calabi-Yau fourfolds for F-theory compactifications dual to heterotic compactifications on a Calabi-Yau threefold with fivebranes wrapping holomorphic curves in the…

Five dimensional field theories with exceptional gauge groups are engineered from degenerations of Calabi-Yau threefolds. The structure of the Coulomb branch is analyzed in terms of relative K\"ahler cones. For low number of flavors, the…

In four-dimensional F-theory compactifications with N=1 supersymmetry the fields describing the dynamics of space-time filling 7-branes are part of the complex structure moduli space of the internal Calabi-Yau fourfold. We explicitly…

We present a discussion of black 2-branes coupled to the fields of the universal hypermultiplet of ungauged N=2 supergravity theory in five dimensions. Using a general ansatz dependent on a spherically symmetric harmonic function, we show…

We consider splitting type phase transitions between Calabi-Yau fourfolds. These transitions generalize previously known types of conifold transitions between threefolds. Similar to conifold configurations the singular varieties mediating…

We construct a covariant bound on the energy-momentum of the M-fivebrane which is saturated by all supersymmetric configurations. This leads to a generalised notion of a calibrated geometry for M-fivebranes when the worldvolume gauge field…

We derive the stability conditions for the M5-brane in topological M-theory using kappa-symmetry. The non-linearly self-dual 3-form on the world-volume is necessarily non-vanishing, as is the case also for the 2-form field strengths on…

We study non-perturbative effects due to a heterotic M-theory five-brane wrapped on Calabi-Yau threefold. We show that such instantons contribute to derivative F-terms described recently by Beasley and Witten rather than to the…

We consider the interplay between brane constructions and type IIA, IIB or M-theory geometries on Calabi-Yau (CY) and G_2 holonomy manifolds. This is related to N=1 (and N=2) gauge theories in four dimensions. We first discuss simple…

We describe how to construct solutions to 11-dimensional supergravity corresponding to M5-branes wrapped on holomorphic 2-cycles embedded in C^3. These solutions preserve N=1 supersymmetry in four dimensions. In the near-horizon limit they…

Using recent results on eleven-dimensional superspace, we compute the contribution of fivebrane instantons with four fermionic zeromodes in M-theory compactifications on Calabi-Yau fourfolds with flux. We find that no superpotential is…

We review recent progress in the construction of four-dimensional vacua of Type II string theory and F-theory which yield the Standard Model of particle physics (SM) or extensions thereof. In Type II orientifold compactifications the SM…

We examine general properties of superembeddings, i.e., embeddings of supermanifolds into supermanifolds. The connection between an embedding procedure and the method of non-linearly realised supersymmetry is clarified, and we demonstrate…

We present a large class of models of D-branes at (orientifold) Calabi-Yau singularities which enjoy dynamical supersymmetry breaking at low energy, by means of either the $SU(5)$ or 3-2 supersymmetry breaking models. Once embedded in a…

F-theory compactified on singular, elliptically fibered Calabi-Yau five-folds gives rise to two-dimensional gauge theories preserving N=(0,2) supersymmetry. In this paper we initiate the study of such compactifications and determine the…