Since 2010, the LHC has produced high quality data on a variety of observables in heavy ion collisions which have already led to exciting new developments in the field, despite of the fact that the LHC has not yet reached to its full power. Complementary to the experimental program a big theoretical effort is needed in order to fully exploit the potential of these data to determine the properties of QCD matter at the highest energy ever achieved in an experiment. In this project we will address some of the most relevant new challenges posed by the theoretical description of ultra-relativistic heavy ion collisions at the LHC. On the one hand we will exploit the gauge/gravity duality to understand the bulk properties of the matter porduced in these collisions, focusing on the characterization of its collective behavior. On the other hand, we will employ perturbative techniques to understand the dynamics of energetic probes propagating through the plasma, focusing in multi-partonic emissions and in the application of effective field theory methods to describe the jet-medium interactions. These theoretical calculations will be complemented with a number of phenomenological studies aimed at confronting them with experimental data.