Brane partons and singleton strings

We examine p-branes in AdS in two limits where they exhibit partonic behavior: rotating branes with energy concentrated to cusp-like solitons; tensionless branes with energy distributed over singletonic bits on the Dirac hypercone. Evidence for a smooth transition from cusps to bits are found. First, each cusp yields D-2 normal-coordinate bound states with protected frequencies; and is dual to a short open p-brane becoming massless on the giant-vacuum brane at the end-of-the-universe. Second, the N-sector is an sp(2N)-gauged phase-space sigma model giving rise to symmetrized N-pletons of the minimal higher-spin algebra ho(D-1,2)⊃so(D-1,2). The continuum limit leads to a 2d chiral sp(2)-gauged sigma model which is critical in D=7; equivalent à la Bars-Vasiliev to an su(2)-gauged spinor string; and furthermore dual to WZW model in turn containing a topological soˆ(6/(soˆ(6)⊕soˆ(2 coset model giving rise to a chiral ring generated by singleton-valued weight-0 spin fields. Moreover, the two-bit truncation leads via a reformulation à la Cattaneo-Felder-Kontsevich to a topological open string on the phase space of the D-dimensional Dirac hypercone giving rise to the Vasiliev equations based on vector oscillators and weak sp(2)-projection. Geometrically, the bi-locality reflects broken boundary-singleton worldlines, and the intertwiner κ relates T- and R-ordered deformations of the boundary and the bulk of the worldsheet, respectively.