Manifestly covariant worldline actions from coadjoint orbits. II. Twistorial descriptions

Worldline actions for various twistor particles in Anti de Sitter (AdS) spacetimes are constructed from the coadjoint orbits of Sp(4,R), SU(2,2), and O∗(8) as constrained Hamiltonian systems. The constraints are associated with the coadjoint orbits of the dual groups, respectively identified as O(p,M-p), U(p,M-p), and Sp(p,M-p). These actions are presented in a universal form by making use of the twistor variables taking values in R, C, and H, respectively. We find that the massless, the massive, and the conformal particles (namely the singletons) of any spins appear for the compact dual groups with p=0 reproducing many of the results in earlier literature, whereas more exotic particle species, such as various tachyons, continuous spin particles, and bitemporal anti de Sitter (BdS) particles appear for the noncompact dual groups.