"Extended operators such as defects are of fundamental importance in conformal field theories, with applications both in high energy theory and in condensed matter systems at criticality. Recently, analytic bootstrap techniques have been successfully applied to study these objects.

In this talk we will focus on the O(3) magnetic impurity, which at the fixed point is described by a defect...

Within the framework of recovering general relativity from scattering amplitudes, it is possible to compute the metric induced by the most generic rotating spherically-symmetric matter configuration at quadrupole order by considering stationary massive spin-1 particles emitting gravitons. This approach leads to a natural definition of a multipole expansion in any dimension and the observation...

DDF operators/states was a formalism first developed by Di Vecchia, Del Giudice and Fubini around 1972. It gives an explicit construction of BRST invariant, not exact (bosonic) string states which I shall briefly recap in the introduction. It is very useful for studying massive string spectra and their scattering amplitudes. After the introduction, the talk will focus on generalising the...

We consider linear scalar perturbartions of JMaRT geometries in type IIB supergravity beyond the near-decoupling limit. In addition to confirm that these solutions suffers of instability for the presence of an ergoregion without horizon, we also find quasi-normal modes (QNMs) with positive imaginary part that can be interpreted in terms of the emission of charged (scalar) quanta with non zero...

Topological stars are smooth horizonless static solutions of Einstein-Maxwell theory in 5-d and they represent possible microstate geometries for non-supersymmetric black holes. They have been proved to be (linearly) stable by studying their spectrum of chargeless quasi-normal modes; their deformability has been analysed through the Tidal Love Number both in the static and the dynamical case....