Abstract We calculate F 4 and RT 4g−4 couplings in d = 8 heterotic and type I string vacua (with gauge and graviphoton field strengths F, T , and Riemann curvature R). The holomorphic piece Fg of the heterotic one–loop coupling R T 4g−4 is given by a polylogarithm of index 5 − 4g and encodes the counting of genus g curves with g nodes on the K3 of the dual F–theory side. We present closed expre...

We discuss why the N6 = 1 heterotic string has to be viewed as something similar to a “non-compact orbifold”. Only the perturbative spectrum is forced to satisfy the constraints imposed by the vanishing of six-dimensional anomalies. These do not apply to the states of the non-perturbative spectrum, such as those appearing when small instantons shrink to zero size. Research supported by the “Mar...

We consider the methods by which higher-level and non-simply laced gauge symmetries can be realized in heterotic string theory. We show that all such realizations have a common underlying feature, namely a dimensional truncation of the charge lattice, and we identify such dimensional truncations with certain irregular embeddings of higher-level and non-simply laced gauge groups within level-one...

Eight-dimensional non-geometric heterotic strings with gauge algebra $\mathfrak{e}_8\mathfrak{e}_7$ were constructed by Malmendier and Morrison as duals of F-theory on K3 surfaces $\Lambda^{1,1}\oplus E_8\oplus E_7$ lattice polarization. Clingher, Shaska extended these constructions to eight-dimensional $\mathfrak{e}_7\mathfrak{e}_7$ E_7\oplus polarized surfaces. In this study, we analyze the p...

A review of orbifold geometry is given, followed by a review of the construction of fourdimensional heterotic string models by compactification on a six-dimensional Z3 orbifold. Particular attention is given to the details of the transition from a classical theory to a first-quantized theory. Subsequently, a discussion is given of the systematic enumeration of all standard-like three generation...

A description is given of how to construct (0, 2) supersymmetric conformal field theories as coset models. These models may be used as non–trivial backgrounds for Heterotic String Theory. They are realised as a combination of an anomalously gauged Wess–Zumino–Witten model, right–moving supersymmetric fermions, and left–moving current algebra fermions. Requiring the sum of the gauge anomalies fr...

Recent interest in superstring unified field theories has been sparked by the discovery of Green and Schwarz' that nonorientable (type I) open and closed superstrings with N = 1 supersymmetry are finite and free of anomalies if the gauge group is SO(32). Previously the only consistent, anomaly-free3 superstring theory was that of orientable (type II) N = 2 supersymmetric closed strings. The new...

M-theory suggests the largeN limit of the matrix description of a collection of N Type IA D-particles should provide a nonperturbative formulation of heterotic string theory. In this paper states in the matrix theory corresponding to fundamental heterotic strings are identified, and their interactions are studied. Comments are made about analogous states in Type IIA string theory, which corresp...

In the note a simple calculation of one loop threshold corrections for the SO(32) heterotic string is performed. In particular the compactification on T 2 with a Wilson line breaking the gauge group to SO(16)×SO(16) is considered. Using heterotic type I duality, these corrections can be related to quantities appearing in the quantum mechanics of type I ′ D0 particles. February 1999 1 email: gut...