A Simple Particle Action from a Twistor Parametrization of AdS5

Abstract The SO (4,2) isometries of AdS 5 are realized non-linearly on its horospherical coordinates ( x m , ρ ). On the other hand, Penrose twistors have long been known to linearly realize these symmetries on 4-dimensional Minkowski space, the boundary of AdS 5 , parametrized by x m . Here we extend the twistor construction and define a pair of twistors, allowing us to include a radial coordinate in the construction. The linear action of SO (4,2) on the twistors induces the correct isometries of AdS 5 . We apply this new construction to the study of the dynamics of a massive particle in AdS 5 . We show that in terms of the twistor variables the action takes a simple form of a 1-dimensional gauge theory. Our result might open up the possibility to find a simple worldvolume action also for the string propagating on AdS 5 .