Continuous-Spin Particles, the on-shell way

par Dr Marcello Romano (IPhT, Saclay)

jeudi 14 nov. 2024, 14:00 → 15:00 Europe/Paris

Salle 1180, bâtiment E2 (Salle des séminaires )

Continuous-Spin Particles (CSPs) arise naturally from Wigner's classification of the unitary representations of the Poincare group. However, defining an interacting (quantum field) theory for these particles is notoriously difficult. In my talk, I will move away from the lagrangian approach and discuss how to bootstrap the S-matrix elements describing the scattering and/or the exchange of CSPs from very generic constraints dictated by Poincaré invariance, little-group covariance, analyticity and unitarity. The resulting amplitudes provide a new infrared deformation of ordinary massless ones, controlled by the scale of the Pauli-Lubanski vector squared. I will mention a few examples, highlighting the essential features of CSPs and open problems.