Jorge Casalderrey-Solana is a Ramón y Cajal Researcher at the Universitat de Barcelona. His research focuses on the properties of QCD matter produced in ultra-relativistic heavy ion collisions. Hong Liu is a Professor of Physics at MIT. His research interests include quantum gravity and exotic quantum matter. David Mateos is an ICREA Research Professor at the Universitat de Barcelona, where he leads a group working on the connection between string theory and quantum chromodynamics. Krishna Rajagopal is a Professor of Physics at MIT. His research focuses on QCD at high temperature or density, where new understanding can come from unexpected directions. Urs Achim Wiedemann is a Senior Theoretical Physicist at CERN, researching the theory and phenomenology of ultra-relativistic heavy ion collisions.