Related papers: E + E $\rightarrow$ H
We determine the anomaly polynomial of the E-string theory and its higher-rank generalizations, that is, the 6d $\mathcal{N} =(1, 0)$ superconformal theories on the worldvolume of one or multiple M5-branes embedded within the…
These lectures intend to give a pedagogical introduction into some of the developments in string theory during the last years. They include perturbative T-duality and non perturbative S- and U-dualities, their unavoidable demand for…
A two-parameter group element is presented that interpolates between M-brane solutions. The group element is used to interpret a number of exotic branes related to the generators of the adjoint representation of E11 as non-marginal half-BPS…
The enhancon mechanism is studied in the heterotic string theory. We consider the N_L=0 winding strings with momentum (NS1-W*) and the Kaluza-Klein dyons (KK5-NS5*). The NS1-W* and KK5-NS5* systems are dualized to the D4-D0* and D6-D2*…
Multistring vertices and the overlap identities which they satisfy are exploited to understand properties of hyperbolic Kac Moody algebras, and $E_{10}$ in particular. Since any such algebra can be embedded in the larger Lie algebra of…
Hypermultiplet couplings in type IIA string theory on a Calabi-Yau space can be quantum corrected by D2-brane instantons wrapping special Lagrangian cycles. On the other hand, hypermultiplet couplings in the heterotic string on a K3 surface…
In analogy to the Schwinger pair production in QED, there exists also the so-called open string pair production for a system of two Dp branes, placed parallel at a separation, with at least one brane carrying a worldvolume electric flux, in…
We study the strong coupling dynamics of the heterotic E_8 x E_8 string theory on the orbifolds T^6/Z_3 and C^3/Z_3 using the duality with the Horava-Witten M-theory picture. This leads us to a conjecture about the low energy description of…
This thesis contributes with a number of topics to the subject of string compactifications. In the first half of the work, I discuss the Hodge plot of Calabi-Yau threefolds realised as hypersurfaces in toric varieties. The intricate…
We consider the general case of N=2 dual pairs of type IIA/heterotic string theories in four dimensions. We show that if the type IIA string in this pair can be viewed as having been compactified on a Calabi-Yau manifold in the usual way…
The conjectured equivalence of the heterotic string to a $K_3$ compactified type IIA superstring is combined with the conjectured equivalence of the latter to a compactified 11-dimensional supermembrane to derive a string membrane duality…
We classify potential cosmic strings according to the topological charge measurable outside the string core. We conjecture that in string theory it is this charge that governs the stability of long strings. This would imply that the SO(32)…
Eight-dimensional nongeometric heterotic strings were constructed as duals of F-theory on $\Lambda^{1,1}\oplus E_8\oplus E_7$ lattice polarized K3 surfaces by Malmendier and Morrison. We study the structure of the moduli space of this…
The recent discovery of an explicit conformal field theory description of Type II $p$-branes makes it possible to investigate the existence of bound states of such objects. In particular, it is possible with reasonable precision to verify…
The reduction of the E8 gauge theory to ten dimensions leads to a loop group, which in relation to twisted K-theory has a Dixmier-Douady class identified with the Neveu-Schwarz H-field. We give an interpretation of the degree two part of…
String and membrane dynamics may be unified into a theory of 2+2 dimensional self-dual world-volumes living in a 10+2 dimensional target space. Some of the vacua of this M-theory are described by the N=(2,1) heterotic string, whose target…
The heterotic string occurs as a soliton of the type I superstring in ten dimensions, supporting the conjecture that these two theories are equivalent. The conjecture that the type IIB string is self-dual, with the strong coupling dynamics…
It is stated in the literature that D-branes in the WZW-model associated with the gluing condition J = - \bar{J} along the boundary correspond to branes filling out the whole group volume. We show instead that the end-points of open strings…
Type II string theory or M-theory contains a broad spectrum of gauge potentials. In addition to the standard $p$-form potentials, various mixed-symmetry potentials have been predicted, which may couple to exotic branes with non-standard…
We study $E_8 \times E_8$-heterotic string on asymmetric orbifolds associated with semi-simple simply-laced Lie algebras. Using the fact that $E_6$-model allows different twists, we present a new N=1 space-time supersymmetric model whose…