High Energy Theory Seminar

Generalized symmetries are an emerging approach for studying quantum field theories. Their study has provided new perspectives on the structure of QFT as well as methods applicable to particle phenomenology. In this talk, based on 2505.03566, we will describe an application of generalized symmetries to particle scattering amplitudes. In particular, we will specify the connection between spontaneously-broken higher symmetries and soft theorems for scattering amplitudes of their associated Nambu-Goldstone bosons. Our main result is a new sub-leading double soft pion theorem in theories with a spontaneously-broken continuous 2-group global symmetry, which intertwines amplitudes with different numbers of pions and photons. We also provide a novel derivation of the leading soft photon theorem from the Ward identity of an emergent 1-form global symmetry in effective field theories where antiparticles are integrated out. Our derivations of these soft theorems use the algebra of spacetime currents and do not rely on asymptotic symmetries or diagrammatic arguments.

Contact [email protected] for Zoom information.