Related papers: Non-perturbative effective interactions from fluxe…

We use open-closed string duality between F-theory on K3xK3 and type II strings on CY manifolds without branes to study non-perturbative superpotentials in generalized flux compactifications. On the F-theory side we obtain the full flux…

In this paper we show that it is possible to derive non-perturbative superpotential terms from a stringy instanton without introducing orientifold planes. The instanton is realized by a Euclidean D brane wrapping a non-trivial cycle upon…

We argue that one can see a specific class of "stringy" D-instantons in the underlying 4D gauge theory as the UV completion of an ordinary gauge instanton of a completely broken gauge group corresponding to the "empty" cycle the D-instanton…

The relative coefficients of higher derivative interactions of the IIB effective action of the form C^4, (D F_5)^4, F_5^8, ... (where C is the Weyl tensor and F_5 is the five-form field strength) are motivated by supersymmetry arguments. It…

We study the potential governing D3-brane motion in a warped throat region of a string compactification with internal fluxes and wrapped D-branes. If the Kahler moduli of the compact space are stabilized by nonperturbative effects, a…

We study K\"ahler moduli stabilizations in semi-realistic magnetized D-brane models based on $ Z_2\times Z_2'$ toroidal orbifolds. In type IIB compactifications, 3-form fluxes can stabilize the dilaton and complex structure moduli fields,…

I use the universal instanton formalism to discuss quantum effects in the open-closed topological string theory of a Calabi-Yau A-model, in the presence of a multiply-wrapped `Floer' D-brane. This gives a precise meaning (up to the issue of…

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…

In this lecture we summarize some recent work on the understanding of instanton effects in string theories with 16 supersymmetries. In particular, we consider F^4 couplings using the duality between the heterotic string on T^4 and type IIA…

The state of the art in D-brane model building is briefly reviewed, focusing on recent achievements in the construction of D=4 N = 1 type II string vacua with semi-realistic gauge sectors. Such progress relies on a better understanding of…

We discuss the effect of the dynamics of D-branes on moduli stabilization in type IIB string theory compactifications, with reference to a concrete toy model of T6/Z3 orientifold compactification with fractional D3-branes and anti-D3-branes…

We consider the couplings induced on the world-volume field theory of D3-branes at local toric Calabi-Yau singularities by euclidean D3-brane (E3-brane) instantons wrapped on (non-compact) holomorphic 4-cycles. These instantons produce…

We study limits of infinite distance in the moduli space of 4d $\mathcal{N} = 2$ string compactifications, in which instanton effects dominate. We first consider trajectories in the hypermultiplet moduli space of type IIB Calabi-Yau…

We calculate gauge instanton corrections to a class of higher derivative string effective couplings introduced in [1]. We work in Type I string theory compactified on K3xT2 and realise gauge instantons in terms of D5-branes wrapping the…

We investigate membrane and fivebrane instanton effects in type IIA string theory compactified on rigid Calabi-Yau manifolds. These effects contribute to the low-energy effective action of the universal hypermultiplet, in four dimensional…

We investigate the D-brane bound states from the viewpoint of the unstable D/\bar{D}-system and their tachyon condensation. We consider two systems; a system of k D(-1)-branes and N D3-branes with open strings connecting them and a system…

We study the $\mathcal N=2$ field theory realized by D3-branes on the ${\mathbb C}^2/{\mathbb Z}_2$ orbifold. The dual supergravity solution exhibits a repulson singularity cured by the enhancon mechanism. By comparing the open and closed…

We introduce and study tetrahedron instantons, which can be realized in string theory by D$1$-branes probing a configuration of intersecting D$7$-branes in flat spacetime with a proper constant $B$-field. Physically they capture instantons…

D3-branes feel no force in no-scale flux compactifications of type IIB string theory, but the nonperturbative effects required to stabilize the Kahler moduli break the no-scale structure and generate a potential for D3-brane motion,…

We derive the non-perturbative corrections to the free energy of the two-matrix model in terms of its algebraic curve. The eigenvalue instantons are associated with the vanishing cycles of the curve. For the (p,q) critical points our…