This work is intended as a pedagogical introduction to M-theory and to its maximally
supersymmetric toroidal compactifications, in the frameworks of 11D supergravity, type II …

The physical motivations and the basic construction rules for type I strings and M-theory
compactifications are reviewed in the light of recent developments. The first part of this …

A bstract We consider gluons scattering in Type IIB string theory on AdS 5× S 5/ℤ 2 in the
presence of D7 branes, which is dual to the flavor multiplet correlator in a certain …

We consider the possibility of breaking the GUT group to the Standard Model gauge group
in F-theory compactifications by turning on certain U(1) fluxes. We show that the requirement …

We obtain the exact non-perturbative thresholds of R4 terms in type 1113 string theory
compactified to eight and seven dimensions. These thresholds are given by the perturbative …

We modify and extend an earlier proposal by Brown and Teitelboim to relax the effective
cosmological term by nucleation of branes coupled to a three-index gauge potential …

We derive the complete (curvature) 2 terms of effective D-brane actions, for arbitrary ambient
geometries and world-volume embeddings, at lowest order (disk-level) in the string-loop …

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 …

The N-point amplitudes for the type II and heterotic superstrings at two-loop order and for N⩽
4 massless NS bosons are evaluated explicitly from first principles, using the method of …

We compute and analyse a variety of four-derivative gravitational terms in the effective
action of six-and four-dimensional type II string ground states with N= 4 supersymmetry. In …