Numerical relativity, the gauge/gravity duality and trans-Planckian scattering have been tremendously active and successful areas in gravitational/high energy physics in recent years. They are strongly motivated by direct experimental connections: gravitational wave detection, probing strong interactions at the Large Hadron Collider (LHC) and at the Relativistic Heavy Ion Collider (RHIC) and even black hole production at the LHC.Numerical relativity methods, applied to black holes, will be essential (and powerful) in studying these high energy physics topics. Such merging is a new born field, pioneered by the proponents. It involves a strong numerical effort, requiring access to supercomputing facilities, expertise in theoretical and phenomenological modeling in high energy physics and contact with research teams working on dedicated experiments in particle accelerators.The necessary numerical relativity techniques have only very recently reached a state of sufficient maturity, which, together with the ongoing scientific runs at LHC and the beginning of science runs for advanced LIGO in the near future make this research programme extremely timely.This action will be instrumental in mainting the existing collaboration and synergies between the proponents, and stimulating European leadership in this flourishing research field.