Description of Research

Prof. Noronha works on a broad range of topics in theoretical physics that lie at the intersect between nuclear physics, string theory, and particle physics. His research uniquely combines string theory, quantum field theory, general relativity, hydrodynamics, and kinetic theory to unravel the novel emergent properties of many-body systems.

His research interests are focused on the non-equilibrium properties of Quantum Chromodynamics (QCD) and the Quark-Gluon Plasma (QGP), nature's primordial liquid created microseconds after the big bang. Using the celebrated gauge/gravity duality, Prof. Noronha and collaborators have determined a number of near equilibrium (transport) properties of the small lump of QGP formed in the ultrarelativistic heavy ion collisions. Also, universal properties of holographic black holes have been recently used to determine the fluctuations of baryon number in a baryon rich QGP and predict the location of the QCD critical point. By combining numerical techniques in general relativity and holography, Prof. Noronha and collaborators performed the first real time out-of-equilibrium calculations in a strongly coupled relativistic liquid that displays critical phenomena.

His work on relativistic hydrodynamics and kinetic theory include the first analytical solution of the Boltzmann equation for a gas in an Friedmann-Robertson-Walker Universe and the development of analytical solutions of relativistic hydrodynamics for heavy ion collisions. Furthermore, Prof. Noronha and collaborators have recently shown that the gradient series, the standard procedure to define hydrodynamics used for nearly a century, has zero radius of convergence both in kinetic theory and in holographic systems. This finding motivates the search for a new consistent way to define hydrodynamics (both at weak and strong coupling) that can be valid even far from equilibrium.

Prof. Noronha has developed interdisciplinary work combining physics and mathematics by recently teaming up with mathematicians to derive a new approach to viscous fluid dynamics coupled to general relativity. In this approach, viscous effects are consistently included in fluid dynamics in the presence of strong gravitational fields and causality, existence, and uniqueness of solutions have been rigorously established via the proof of two theorems.

Research interests also include the role played by strong magnetic fields in the cold and dense core of neutron stars, the dynamics of jets in the quark-gluon plasma, and the non-equilibrium dynamics of non-Abelian gauge fields in curved spacetime.

## Prof. Noronha works on a variety of questions in theoretical physics such as:

- What is the behavior of matter at ultrahigh temperatures and/or densities?

- What are the novel collective states of matter that emerge in systems far from equilibrium?

- How does a chunk of fluid behave when moving close to the speed of light?

Full list of scientific publications can be found here or here.