Speaker
Description
When describing particle collisions, we usually approximate the initial-state particles as plane waves. The fact that in reality they are wave packets does not usually play any role. However, the past two decades witnessed the emergence of a new intriguing class of wave packets called vortex states. A photon, an electron, or any other particle prepared in a vortex state is characterized by helicoidal wave fronts, and as a result, it carries a nonzero orbital angular momentum (OAM) projection on its propagation direction. This is a new, adjustable quantum number, unrelated to spin, which has never been exploited in experimental nuclear and particle physics. Low-energy vortex photons, electrons, and neutrons have already been demonstrated in experiment, and there exist proposals for generating vortex particles with MeV and GeV energies. Anticipating future experimental progress, one can ask what additional insights into hadron structure will follow once collisions of high-energy vortex states become feasible. In this talk, I will give an broad overview of this topic, focusing on new observables that emerge in vortex scattering.
