We give necessary conditions for the existence of perturbative heterotic and common sector type II string warped compactifications preserving four and eight supersymmetries to four spacetime dimensions, respectively. In particular, we find that the only compactifications of heterotic string with the spin connection embedded in the gauge connection and type II strings are those on Calabi-Yau man...

We review quantitative tests on the duality between the heterotic string on T 2 and F -theory on K3. On the heterotic side, certain threshold corrections to the effective action can be exactly computed at one-loop order, and the issue is to reproduce these from geometric quantities pertaining to the K3 surface. In doing so we learn about certain nonperturbative interactions of 7-branes.

We compute the gravitational coupling F1 for IIA string theory on K3× T 2 and use string-string duality to deduce the corresponding term for heterotic string on T . The latter is an infinite sum of gravitational instanton effects which we associate with the effects of Euclidean fivebranes wrapped on T . These fivebranes are the neutral fivebranes or zero size instantons of heterotic string theory.

We collect further evidence for the proposed duality between N = 2 heterotic and type II string vacua in a specific model suggested by Kachru and Vafa. In the gauge sector the previous analysis is extended; it is further shown that the duality also holds for the one–loop gravitational couplings to the vector multiplets. ⋆ Research supported in part by: the NSF, under grant PHY–90–09850 (V.K.); ...

We study heterotic vacua with four supercharges in three and four space-time dimensions and their duals obtained as M/F-theory compactified on Calabi-Yau fourfolds. We focus on their respective moduli spaces and derive the Kähler potential for heterotic vacua obtained as circle compactifications of four-dimensional N = 1 heterotic theories. The Kähler potential of the dual theory is computed by...

We address the question of finding stable and metastable cosmic strings in quasirealistic heterotic M-theory compactifications with stabilized moduli. According to Polchinski’s conjecture, the only stable strings in the absence of massless fields are Aharonov-Bohm strings. Such strings could potentially be created in heterotic compactifications as bound states of open membranes, five-branes wra...

We systematically analyse the necessary and sufficient conditions for the preservation of supersymmetry for bosonic geometries of the form R1,9−d ×Md, in the common NS-NS sector of type II string theory and also type I/heterotic string theory. The results are phrased in terms of the intrinsic torsion of G-structures and provide a comprehensive classification of static supersymmetric backgrounds...

We introduce and define 'heterotic computing' as a combination of two or more computational systems such that they provide an advantage over either substrate used separately. This first requires a definition of physical computation. We take the framework in Horsman et al. (Horsman et al. 2014 Proc. R. Soc. A 470, 20140182. (doi:10.1098/rspa.2014.0182)), now known as abstract-representation theo...

We explore the moduli space of heterotic strings in two dimensions. In doing so, we introduce new lines of compactified theories with Spin(24) gauge symmetry and discuss compactifications with Wilson lines. The phase structure of d = 2 heterotic string theory is examined by classifying the hypersurfaces in moduli space which support massless quanta or discrete states. Finally, we compute the to...

Using the topological membrane approach to string theory, we suggest a geometric origin for the heterotic string. We show how different membrane boundary conditions lead to different string theories. We discuss the construction of closed oriented strings and superstrings, and demonstrate how the heterotic construction naturally arises from a specific choice of boundary conditions on the left an...