Physics of Deformed Special Relativity: Relativity Principle revisited

TL;DR

This paper revisits Deformed Special Relativity (DSR), proposing a consistent framework that extends the relativity principle to include mass, employs a 5D perspective, and resolves conceptual issues like the soccer ball problem.

Contribution

It introduces a 5D approach to DSR, extending symmetry groups and redefining multi-particle states, providing a clearer physical interpretation and resolving key conceptual problems.

Findings

Resolution of the soccer ball problem

Interpretation of non-commutativity in DSR

Extension of symmetry to Poincare-de Sitter group

Abstract

In many different ways, Deformed Special Relativity (DSR) has been argued to provide an effective limit of quantum gravity in almost-flat regime. Some experiments will soon be able to test some low energy effects of quantum gravity, and DSR is a very promising candidate to describe these latter. 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 5-dimensional point of view on DSR physics and the extension of the kinematical symmetry from the Poincare group to the Poincare-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 kappa. 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. In particular, the coproduct of the kappa-Poincare algebra is interpreted as defining the law of change of reference frames and not the law of scattering. This point of view places DSR as a theory, half-way between Special Relativity and General Relativity, effectively implementing the Schwarzschild mass bound in a flat relativistic context.