Infrared-safe positivity bounds with long-range interactions

by Marcello Romano (EPFL)

Tuesday 27 Oct 2026, 14:00 → 15:00 Europe/Zurich

4/3-006 - TH Conference Room (CERN)

Long-range interactions make generic observables sensitive to the infrared structure of the theory. For instance photons and/or gravitons force exclusive S-matrix elements to vanish in D=4 flat space-time, due to infrared divergences. This poses a challenge to programs, such as positivity and S-matrix bootstrap, that directly rely on the properties of 2-to-2 amplitudes. In this talk, I will introduce stripped amplitudes as IR-safe, analytic, crossing-symmetric, and Regge-behaved avatars of standard amplitudes, associated with a physical detector scale \E. In the regime in which the latter is taken exponentially small than all other scales, they also satisfy a form of unitarity, allowing to derive IR-safe positivity bounds on EFTs, in presence of long-range interactions.