2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/198730We describe few aspects of the quantum symmetries of some massless two-dimensional field theories. We discuss their relations with recent proposals for the factorized scattering theories of the massless $PCM_1$ and $O(3)_{θ=π}$ sigma models. We use these symmetries to propose massless factorized S-matrices for the $su(2)$ sigma models with topological terms at any level, alias the $PCM_k$ models, and for the $su(2)$-coset massless flows.13 pagesHigh Energy Physics - Theorytext