Related papers: The structure of the R^8 term in type IIB string t…
We realize the 16 unbroken supersymmetries on a BPS D-brane as invariances of the action of the corresponding open superstring field theory. We work in the small Hilbert space approach, where a symmetry of the action translates into a…
These lecture notes begin with a review of the first nonleading contributions to the derivative expansion of the M theory effective action compactified on a two-torus. The form of these higher-derivative interactions is shown to follow from…
The two-loop Feynman diagram contribution to the four-graviton amplitude of eleven-dimensional supergravity compactified on a two-torus, T^2, is analyzed in detail. The Schwinger parameter integrations are re-expressed as integration over…
The $S^N\R^8$ supersymmetric orbifold sigma model is expected to describe the IR limit of the Matrix string theory. In the framework of the model the type IIA string interaction is governed by a vertex which was recently proposed by…
We study the origins of the five ten-dimensional ``matrix superstring'' theories, supplementing old results with new ones, and find that they all fit into a unified framework. In all cases the matrix definition of the string in the limit of…
Certain one-loop processes in eleven-dimensional supergravity compactified on T**2 determine exact, non-perturbative, terms in the effective action of type II string theories compactified on a circle. One example is the modular invariant…
Twisted supergravity is supergravity in a background where the bosonic ghost field takes a non-zero value. This is the supergravity counterpart of the familiar concept of twisting supersymmetric field theories. In this paper, we give…
We point out that type I string theory in the presence of internal magnetic fields provides a concrete realization of split supersymmetry. To lowest order, gauginos are massless while squarks and sleptons are superheavy. We build such…
New non-perturbative interactions in the effective action of two dimensional string theory are described. These interactions are due to ``stringy" instantons
It has been speculated that the metric, $B$-field and dilaton couplings in the low energy effective action of string theory at any order of $\alpha'$ may be found by imposing the gauge symmetries and the T-duality on the effective action.…
In this work, we uncover a collection of non invertible topological operators linked to the 0-, 2-, 4- and 6-form symmetries related to the type IIB superstring effective theory. By pinpointing the $\text{SL}(2,\mathbb{Z})$-covariant…
We study leading string corrections to the type IIB supergravity solution dual to the ${\cal N}=1$ supersymmetric $SU(N+M)\times SU(N)$ gauge theory coupled to bifundamental chiral superfields $A_i, B_j$, $i,j=1,2$. This solution was found…
We consider a string theory with two types of strings with geometric interaction. We show that the theory contains strings with constant Dirichlet boundary condition and those strings are glued together by 2-d topological gravity with…
D-brane technology and strong/weak coupling duality supplement traditional orbifold techniques by making certain background geometries more accessible. In this spirit, we consider some of the geometric properties of the type IIB theory on…
Complimentary geometric and non-geometric consistent reductions of IIB supergravity are studied. The geometric reductions on the identified group manifold X are found to have a gauge symmetry with Lie algebroid structure, generalising that…
The full two-loop amplitudes for five massless states in Type~II and Heterotic superstrings are constructed in terms of convergent integrals over the genus-two moduli space of compact Riemann surfaces and integrals of Green functions and…
We give simple arguments for new non-renormalization theorems on higher derivative couplings of gauge theories to supergravity, with sixteen supersymmetries, by considerations of brane-bulk superamplitudes. This leads to some exact results…
Certain scattering amplitudes in the gravitational sector of type II string theory on K3 x T^2 are found to be computed by correlation functions of the N=4 topological string. This analysis extends the already known results for K3 by…
Motivated by the string theory analysis of arXiv:1108.6331, we construct a class of 1/8-BPS solutions of type IIB supergravity compactified on S^1 x T^4. In this duality frame our ansatz allows for a non-trivial NS-NS B-field which has been…
0-brane of type IIA string theory can be interpreted as a dimensional reduction of a gravitational wave in 11 dimensions. We observe that a similar interpretation applies also to the D-instanton background of type IIB theory: it can be…