相关论文: Matching the BPS Spectra of Heterotic - Type I - T…

Type II strings in D=5 contain particle-like 1/8 supersymmetric BPS states. In this note we give a string-network representation of such states by considering (periodic) non-planar $(p,q,r)$-string networks of eight dimensional type II…

We test the prediction of a hagedorn density of BPS states which carry RR charge in type II compactifications. We find that in certain cases they correspond to the supersymmetric ground states for a gas of identical 0-branes.

E8 X E8 heterotic string and M-theory, when appropriately compactified, can give rise to realistic, N=1 supersymmetric particle physics. In particular, the exact matter spectrum of the MSSM, including three right-handed neutrino…

Certain four-dimensional $N=4$ supersymmetric theories have special vacua in which massive charged vector supermultiplets become massless, resulting in an enhanced non-abelian gauge symmetry. We show here that any two $N=4$ theories having…

A new class of higher-spin gauge theories associated with various Coxeter groups is proposed. The emphasize is on the $B_p$--models. The cases of $B_1$ and its infinite graded-symmetric product $sym\,(\times B_1)^\infty$ correspond to the…

We investigate orbifold compactifications of the heterotic string, addressing in detail their construction, classification and phenomenological potential. We present a strategy to search for models resembling the minimal supersymmetric…

We study the dynamics of D-particles (D0-branes) in type I' string theory and of the corresponding states in the dual heterotic description. We account for the presence of the two 8-orientifolds (8 dimensional orientifold planes) and…

We propose a configuration of D-branes welded by analogous orbifold operation to be responsible for the enhancement of $SO(2N)$ gauge symmetry in type II string compactified on the $D_n$-type singular limit of K3. Evidences are discussed…

Type IIB string theory admits a BPS configuration in which three strings (of different type) meet at a point. Using this three string configuration we construct a string network and study its properties. In particular we prove supersymmetry…

The moduli space of toroidal type I vacua, which are consistent at the non-perturbative level, consists of independent branches characterized by the number (0, 16 or 32) of rigid branes sitting on top of orientifold planes. This structure…

We describe the counting of BPS states of Type II strings on K3 by relating the supersymmetric cycles of genus $g$ to the number of rational curves with $g$ double points on K3. The generating function for the number of such curves is the…

Considering SO(32) heterotic string theory compactified on a torus of dimension 4 and less, stability of non-supersymmetric states is studied. A non-supersymmetric state with robust stability is constructed, and its exact stability is…

Orbifold compactification of heterotic E8 x E8 string theory is a source for promising grand unified model building. It can accommodate the successful aspects of grand unification while avoiding problems like doublet-triplet splitting in…

In this article we study D1-D3 (or $\bar{\textrm{D}3}$) brane systems with generic constant electric and magnetic fluxes in IIB string theory. We work out all possible supersymmetric configurations and find out via T-duality all of them and…

BPS spectra give important insights into the non-perturbative regimes of supersymmetric theories. Often from the study of BPS states one can infer properties of the geometrical or algebraic structures underlying such theories. In this paper…

The data required for heterotic string theory with gauge group G, which for anomaly cancellation reasons must either be E8 x E8 or Spin(32)/Z2, consist of the following: a ten-dimensional space-time X and a principal G-bundle P. The fields…

We present a Z_6 orbifold compactification of the E_8xE_8 heterotic string which leads to the (supersymmetric) Standard Model gauge group and matter content. The quarks and leptons appear as three 16-plets of SO(10), whereas the Higgs…

It has been shown that D0-D$p$ $(p=2, 4, 6, 8)$ systems can be BPS in the presence of $B$-field even if they are not otherwise. We review the number of remaining supersymmetries, the open string ground state spectrum and the construction of…

We derive the BPS mass formulae of the Dirichlet branes from the Born-Infeld type action. BPS saturation is realized when the brane has the minimal volume while keeping the appropriate winding numbers. We apply the idea to two cases, type…

We show how splitting supersymmetry reconciles a class of intersecting brane models with unification. The gauge sector in these models arises in multiplets of extended supersymmetry while matter states are in N=1 representations. A…