Our work on Gravitational Physics covers a wide range of classical and quantum aspects of gravity and black holes. Many of the questions we address revolve around the fundamental nature of horizons and singularities in spacetime: What is a quantum black hole? How does spacetime emerge out of the quantum entanglement of more fundamental degrees of freedom? How should we interpret the appearance of singularities in Einstein’s theory, and what do they reveal about quantum gravity? Holography is often the framework where we investigate these questions most effectively.

In Cosmology, we explore the implications of inflationary models, cosmology of the early and present universe, axions, semiclassical gravity, as well as the formation and cosmological implications of primordial black holes. We are also involved in the study of possible Stochastic Gravitational Wave Backgrouns of cosmological origin, which may be probed by existing and future detectors.

Our research encompasses many aspects of Quantum Field Theory, from the most phenomenological, as described in Particle Physics Phenomenology, to the most formal. The latter include the study of conformal or supersymmetric theories in different numbers of dimensions, both in their own right and in connection with the Gauge/String Duality. In parallel with this, the crucial role of entanglement in the foundations of quantum field theory and in holography has come to the fore in recent years, and we are contributing to unraveling its structural properties and consequences.

In String Theory our activities span a wide array of topics such as the dynamics of branes, the study of the fundamental symmetries of String Theory, the determination of 1/N corrections in the gauge/string duality (with N the rank of the gauge group), and the identification of non-relativistic limits of the duality. As a quantum theory of gravity, String Theory also has profound implications for the microphysics of black holes, directly linking to our research in gravity.

One fundamental aspect of the Gauge/String Duality is that it maps the strong coupling, large-N regime of the gauge theory to the regime on the string side in which the theory reduces to classical gravity. Exploiting this connection, we use classical gravity to study regimes of Quantum Chromodynamics inaccessible by conventional techniques. These include the far-from-equilibrium dynamics of the Quark-Gluon Plasma created in heavy ion collisions or the properties of dense quark matter that could be present at the core of neutron stars. More recently, we have spearheaded cosmological applications of holography such as the possible generation of primordial Gravitational Waves in phase transitions in the early Universe.

Holography is thus a prime example of synergy at work at the ICCUB: By connecting fields as diverse as Quantum Field Theory, String Theory, Gravitation, Cosmology, Gravitational Waves, Particle Physics and Nuclear Physics, it weaves together the varied textures of our research.