Related papers: Spectrum of CHL Dyons from Genus-Two Partition Fun…
A deformation of the N=2 topological string partition function is analyzed by considering higher dimensional F-terms of the type W^{2g}*Upsilon^n, where W is the chiral Weyl superfield and each Upsilon factor stands for the chiral…
We study closed N=2 strings on orbifolds of the form T^4/Z_2 and C^2/Z_2. We compute the torus partition function and prove its modular invariance. We analyse the BRST cohomology of the theory, construct the vertex operators, and compute…
The two-loop chiral measure for superstring theories compactified on $\bZ_2$ reflection orbifolds is constructed from first principles for even spin structures. This is achieved by a careful implementation of the chiral splitting procedure…
Three-dimensional string models with half-maximal supersymmetry are believed to be invariant under a large U-duality group which unifies the S and T dualities in four dimensions. We propose an exact, U-duality invariant formula for…
We compute a twisted index for an orbifold theory when the twist generating group does not commute with the orbifold group. The twisted index requires the theory to be defined on moduli spaces that are compatible with the twist. This is…
We present orientifold and F-theory duals of the heterotic string compactification constructed by Chaudhuri, Hockney and Lykken (CHL) which has the maximal supersymmetry but gauge group of reduced rank. The 8-dimensional dual is given by…
We construct a general class of chiral four-dimensional string models with Scherk--Schwarz supersymmetry breaking, involving freely acting orbifolds. The basic ingredient is to combine an ordinary supersymmetry-preserving Z_N projection…
The D-brane spectrum of a class of $\Zop_2$ orbifolds of toroidally compactified Type IIA and Type IIB string theory is analysed systematically. The corresponding K-theory groups are determined and complete agreement is found. The charge…
The dominant contribution to the semicanonical partition function of dyonic black holes of N=4 string theory is computed for generic charges, generalizing recent results of Shih and Yin. The result is compared to the black hole free energy…
We propose a bosonic string dual to large $N$ chiral Yang-Mills in two dimensions at finite 't Hooft coupling. The worldsheet theory is a $\beta$-$\gamma$ system deformed by a chiral Polchinski-Strominger term. We reproduce the partition…
CHL compactifications are supersymmetry preserving orbifolds of any perturbatively renormalizable and ultraviolet finite ground state of the perturbative string theories: heterotic, type I, or type II, preserving 32, 16, 12, 8, 4, (or zero)…
We study the topological string partition function of a class of toric, double elliptically fibered Calabi-Yau threefolds $X_{N,M}$ at a generic point in the K\"ahler moduli space. These manifolds engineer little string theories in five…
We revisit the construction of self-dual field theory in 4l+2 dimensions using Chern-Simons theory in 4l+3 dimensions, building on the work of Witten. Careful quantization of the Chern-Simons theory reveals all the topological subtleties…
Compactifications of the heterotic string on special T^d/Z_2 orbifolds realize a landscape of string models with 16 supercharges and a gauge group on the left-moving sector of reduced rank d+8. The momenta of untwisted and twisted states…
Chern-Simons gauge theory is formulated on three dimensional $Z_2$ orbifolds. The locus of singular points on a given orbifold is equivalent to a link of Wilson lines. This allows one to reduce any correlation function on orbifolds to a sum…
We investigate the $Q^{2}$-evolution of the chiral-odd spin-dependent parton distribution $h_{L}(x, Q^{2})$ relevant for the polarized Drell-Yan processes. The results are obtained in the leading logarithmic order in the framework of the…
The slice-independent gauge-fixed superstring chiral measure in genus 2 derived in the earlier papers of this series for each spin structure is evaluated explicitly in terms of theta-constants. The slice-independence allows an arbitrary…
We give a manifestly U-duality invariant formula for the degeneracy of 1/8 BPS dyons in type II string theory on T^6 for a U-duality invariant subset of charge vectors. Besides depending on the Cremmer-Julia invariant the degeneracy also…
The topological string partition function Z=exp(lambda^{2g-2} F_g) is calculated on a compact Calabi-Yau M. The F_g fulfill the holomorphic anomaly equations, which imply that Z transforms as a wave function on the symplectic space…
For heterotic string theory compactified on T^6, we derive the complete set of T-duality invariants which characterize a pair of charge vectors (Q,P) labelling the electric and magnetic charges of the dyon. Using this we can identify the…