We will discuss how amplitudes can be used to efficiently derive classical gravitational-wave observables characterizing black hole binary encounters. This technique is very flexible and can be applied to General Relativity, but also to its extensions and, in the spirit of Effective Field Theory, can be used to describe compact objects beyond Schwarzschild black holes. We will briefly discuss some recent applications to spinning black holes and to the subleading Post-Minkowsian waveforms.

There are indications that "traditional" GR physics at the horizon and usual assumptions of locality cannot provide a consistent description of black holes. The fuzzball paradigm suggests that "traditional" GR physics at the horizon should be relaxed and that string theory provides the right degrees of freedom to have a non-trivial structure at the scale of the horizon. I'll review how this idea has emerged from the analysis of the Strominger-Vafa black hole and its implication for the AdS3/CFT2 duality. For link to the meeting, please email damian.galante@kcl.ac.uk.

The AdS/CFT duality maps supersymmetric heavy operators with conformal dimension of the order of the central charge to asymptotically AdS supergravity solutions. I'll show how, by studying the quadratic fluctuations around such backgrounds, it is possible to derive 4-point correlators of two light and two heavy states in the supergravity approximation. Then by using this input, I'll discuss how to reconstruct standard supergravity correlators between four (single particle) operators. I'll present some explicit examples in the AdS3 setup relevant for the duality with the D1-D5 CFT.

The AdS/CFT duality maps supersymmetric heavy operators with conformal dimension of the order of the central charge to asymptotically AdS supergravity solutions. I'll show how by studying the quadratic fluctuations around such backgrounds it is possible to derive the 4-point correlators of two light and two heavy states in the supergravity approximation. I'll present some explicit examples in the AdS3 setup relevant for the duality with the D1-D5 CFT and discuss what we can learn in general about correlators among heavy pure states.

Lecture 3: An example of mixed open/closed amplitudes

Lecture 2: Derivation of the Virasoro-Shapiro amplitude; 4 graviton amplitude in the superstring (no derivation, but discussion of the low and high energy limits)

Lecture 1: Veneziano amplitude: derivation, low and high energy limits

The study of high energy amplitudes in string theory provides an interesting arena to study several issues in quantum theories of gravity. I will focus on a conceptually very simple situation where a perturbative graviton scatters against a stack of D-branes and I will discuss phenomena, such as the emergence of tidal forces, the restoration of unitarity through resummation of diagrams and how the Regge behaviour of string theory is crucial to avoid causality violations

I will reconsider toroidal compactifications of bosonic string theory with particular regard to the phases (cocycles) necessary for a consistent definition of the vertex operators, the boundary states, and the T-duality rules. I will then use these ingredients to compute the planar multi-loop partition function describing the interaction among magnetised or intersecting D-branes. Finally I will examine the degeneration limit of the 2-loop partition function and show that one obtains known and new tree-level 3-point correlators between twist fields.

I will discuss the main features of the string compactifications with magnetized (or equivalently intersecting) D-branes and explain why they represent a very interesting setup for phenomenological applications. In particular, I will discuss how to use string techniques to systematically derive brane world effective actions for models with magnetized (or equivalently intersecting) D-branes.

I will discuss how to use string techniques to systematically derive brane world effective actions for models with magnetized (or equivalently intersecting) D-branes. In particular, I derive the dependence on all NS-NS moduli of the kinetic terms of the chiral matter in a generic non-supersymmetric brane configurations with non-commuting open string fluxes. Near a N=1 supersymmetric point the effective action contains D and F term breaking terms which can be explicitly computed with string diagrams.