Physics of Deformed Special Relativity: Relativity Principle Revisited

In many different ways, Deformed Special Relativity (DSR) has been argued to provide an effective limit of quantum gravity in almost-flat regime. Unfortunately, DSR is up to now plagued by many conceptual problems (in particular how it describes macroscopic objects) which forbids a definitive physical interpretation and clear predictions. Here we propose a consistent framework to interpret DSR. We extend the principle of relativity: the same way that Special Relativity showed us that the definition of a reference frame requires to specify its speed, we show that DSR implies that we must also take into account its mass. We further advocate a 5dimensional point of view on DSR physics and the extension of the kinematical symmetry from the Poincaré group to the Poincaré-de Sitter group (ISO(4, 1)). This leads us to introduce the concept of a pentamomentum and to take into account the renormalization of the DSR deformation parameter κ. This allows the resolution of the “soccer ball problem” (definition of many-particle-states) and provides a physical interpretation of the non-commutativity and non-associativity of the addition the relativistic quadrimomentum.