As is well known, the string spectrum comprises infinitely many physical states organized in levels of increasing mass and spin. Among them, there appear infinitely many massive higher spins, which are crucial to several of the central properties of string theory, such as the absence of UV divergences in string scattering amplitudes. Yet what do these states look like? Past research has mainly focused on the lightest levels and the leading Regge trajectory, while traditional methodologies offer in principle access to any level, but their output is not immediately given in irreducible representations of the Wigner little group. In this seminar, we will discuss a new and covariant technology of excavating entire physical trajectories, deeper in the open bosonic string and superstring spectrum. It is based on the observation that the Virasoro constraints, which guarantee the physicality of string states, entails generators of a bigger algebra, that is a symplectic algebra which commutes with the spacetime Lorentz algebra. Deeper trajectories can then be reached by suitably acting with the raising operators of the symplectic algebra on simpler trajectories with the same spacetime symmetries.
Videoconference via https://us02web.zoom.us/j/88470557426