Related papers: Stringy Instanton Effects in Models with Rigid Mag…

We show that non-Spin cycles in type IIB Calabi-Yau orientifold compactifications with vanishing B field naturally support orientifold-invariant D-brane instantons. These instantons, associated to the holomorphic cotangent bundle of the…

We consider aspects of instanton dynamics in the large-N limit using the AdS/CFT duality for D0/D4 bound states. In the supergravity picture of wrapped D0-brane world-lines on D4-branes, we find the single-instanton measure and discuss its…

We study the relation between the ADHM construction of instantons in the Omega-background and the fractional D3/D(-1)-branes at the orbifold singularity of C \times C^2/Z_2 in Ramond-Ramond (R-R) 3-form field strength background. We…

The role of instantons in describing non-perturbative aspects of globally supersymmetric gauge theories is reviewed. The cases of theories with N=1, N=2 and N=4 supersymmetry are discussed. Special attention is devoted to the intriguing…

We discuss construction and applications of instanton-like objects which we call fractional space-like branes. These objects are localised at a fixed point of a time-like (or more generally space-time) orbifold which is a string theoretical…

The instanton vacuum picture is used to study hadronic matrix elements of the twist-3 (dimension-4, spin-1) QCD operators measuring the quark spin density and spin-orbit correlations. The QCD operators are converted to effective operators…

Following the recent work of hep-th/0405076 we discuss the emergence of D-brane instanton solutions in c=0 noncritical string theory. Our emphasis is on finding the D-instanton effects in a field theoretic setting. Using the framework of…

We analyse some physical consequences when supersymmetry is broken by a set of D-branes and/or orientifold planes in Type II string theories. Generically, there are global dilaton tadpoles at the disk level when the transverse space is…

D-branes on orbifolds with and without discrete torsion are analysed in a unified way using the boundary state formalism. For the example of the Z2 x Z2 orbifold it is found that both the theory with and without discrete torsion possess…

Instanton contributions in 2d string theory are known to include subtle numerical factors $\zeta_n$ closely related to a contour prescription in multi-instanton string amplitudes. Both ingredients appear to be ambiguous due to a degeneracy…

We investigate string amplitudes by using the partial modular transformation which we introduced in our previous works. This enables us to extract stringy threshold corrections from the full string amplitudes and interpret them in terms of…

We study the behavior of the effective potential between revolving D$p$-branes at all ranges of the distance $r$, interpolating $r \gg l_s$ and $r \ll l_s$ ($l_s$ is the string length). Since the one-loop open string amplitude cannot be…

We show that discrete torsion is implemented in a D-brane world-volume theory by using a projective representation of the orbifold point group. We study the example of C^3/Z_2 x Z_2 and show that the resolution of singularities agrees with…

We elucidate the structure of D terms in N=1 orientifold compactifications with fluxes. As a case study, we consider a simple orbifold of the type-IIA theory with D6-branes at angles, O6-planes and general NSNS, RR and Scherk-Schwarz…

Some of the properties of string theory defined on world-sheets with boundaries are reviewed. Particular emphasis is put on the possibility of identifying string configurations (\lq D-instantons' and \lq D-branes') that give rise to stringy…

The FZZT and ZZ branes in (p,p+1) minimal string theory are studied in terms of continuum loop equations. We show that systems in the presence of ZZ branes (D-instantons) can be easily investigated within the framework of the continuum…

We study D-instanton contributions to supergraviton scattering amplitudes in the ten-dimensional type IIB superstring theory beyond the leading non-perturbative order. In particular, we determine the one-D-instanton contribution to maximal…

We compute the partition function for the exotic instanton system corresponding to D-instantons on D7 branes in Type I' theory. We exploit the BRST structure of the moduli action and its deformation by RR background to fully localize the…

In systems with local gauge symmetries, the memory effect corresponds to traces inscribed on a suitable probe when a pure gauge configuration at infinite past dynamically evolves to another pure gauge configuration at infinite future. In…

By reduction along the time direction, black holes in 4 dimensions yield instantons in 3 dimensions. Each of these instantons contributes individually at order $\exp(-|Q|/g_s)$ to certain protected couplings in the three-dimensional…